"You never say thank you."
"That's what the money's for."
- The Suitcase Season 4, Episode 7 
On Peggy Olson's 26th birthday, her night was ruined by her lush of a boss who wasn't satisfied with her tag line for Samsonite and so, made her miss a birthday dinner and with it, a boyfriend who couldn't tolerate being second fiddle to her work. Of course, what was happening that night had little to do with a tag line for a suitcase, it was about a man who did not want to hear the news of the passing of the one person in his life who knew and loved him, as flawed as he was. It was about someone not wanting to face the cold reality of life, and so, took out that frustration and fear on the only person he knew could take it. But in the end, after a night of soul baring and emotional intimacy, when Don finally made that fateful call and confirmed what he already knew to be true, he and Peggy shared a tender moment, his hand gently enclosing hers, appearing to cement a bond that had been long in forming.
It's no surprise that the few glimpses of Don's desk we see include a photo of him and Anna Draper, but four years (and a few weeks) later, he and Peggy re-convene in that same office, but with quite a bit of water under the bridge. Instead of deepening a bond that had been built ever since Don put Peggy on the Belle Jolie account,  had deepened when Don visited Peggy in the hospital where she was recuperating from the birth of her child,  become more complicated when Peggy came to the rescue after Don crashed Bobbi Barrett's car,  and survived the launch of Sterling Cooper Draper Pryce,  The Suitcase was a high water mark after which Peggy and Don's relationship dissolved, slowly at first, but over time, much more quickly. First, Megan supplanted Peggy as Don's emotional nourishment;  then, when Megan quit the firm to try her hand at acting, Don blamed Peggy,  riding her mercilessly until she quit and took another job. 
The merger of SCDP and CGC brought Peggy back into Don's orbit,  but by this time, Don's blackened soul and Peggy's unrequited desire for Ted were on a collision course. Peggy has been nursing a rather stiff grudge against Don for "breaking" Ted, for crushing his spirit by dangling the threat of the revelation of their affair to a client  and shaming Ted, who Peggy viewed as virtuous, into absconding to California with his wife Nan and two boys in tow.  Of course, that was just the cherry on the sundae for years of verbal abuse, dismissiveness and humiliation that Don piled on her, but the tent poles for The Strategy were these two beautifully acted (and written) scenes between Peggy and Don that took place in Don's old office (now occupied by the odious Lou Avery) that buried the hatchet of all of that rancor. There, after Peggy had her tantrum, drunk dialed Don and tried to get pissy with him, each laid bare their fears and insecurities.
The pitch for Burger Chef was not about mom's battle with fast food any more than Don cared about what was being offered for Samsonite way back in 1965 (a year Peggy and Don ruminate over in one of the scenes). Instead, it stood as a convenient proxy for Peggy's own perception of herself - of being a single woman at 30 unable to relate to being a mother and unsure about what families do, and to give Don an opportunity to be tender and paternal - to be supportive in ways he rarely was when the power dynamic was reversed, to acknowledge that he feared having done nothing and having no one in his life and not wanting Peggy to suffer the same fate. To tell her, because only he can and have it matter to her, that she is doing just fine. Because to both of them, nothing outside the office will ever seem as important as what happens in the office, because Peggy knows Don better than anyone and heard in his floating of the pitch from a child's point of view that he wasn't wild about the agreed upon strategy. But here, instead of being competitive with Peggy, of bickering over her desire to be placed on accounts or dismissing her ideas as kernels that he turns into CLIO award winning material, he is instead charitable and mentoring - walking her through the creative process that goes on inside his head without rubbing her nose in it or feeling the need to save the day.
The call back to The Suitcase was unmistakable but also distinct. The Don of 1969 is a world-wearier person. For all the attention we draw to his lack of empathy or (self) awareness, he is stung by the slings and arrows of bad fortune. He may blanch at most of the rules placed upon him by the other partners (although it seems he's broken most of them in spirit if not by their letter), but he found an untapped reservoir of good will toward Peggy that was absolutely endearing and afforded him the wherewithal to put himself in service of someone who he obviously values. The two scenes between Don and Peggy are interesting in that the way they were scripted placed Peggy in the power position - she was the boss, but there was almost a Yoda/Luke Skywalker vibe to it - she'd like to underscore the possibility that the pitch could involve the mother coming home from work, but Don knows that is a story that people are not yet ready to hear. He isn't pressing to make his idea the winner, but rather, nurturing and nursing her in the way a teacher might aid a prized pupil who is on the cusp of achieving something great.
And because of that, she finds her theme - family - whether it's around a kitchen table or strangers sitting in a restaurant, who you are with defines who you are. In so many ways, the entire arc of Mad Men has been about that quest to, as Bob Benson put it, find comfort in an uncertain world. Don long ago noted that he felt as if he was just outside his own life, trying to scratch his way into it,  but everyone else has wrestled with those same demons. Joan walked into a marriage with a man who thought nothing of sexually assaulting her in a fit of pique  because marriage and appearances mattered, it was not long after Pete married Trudy that he was telling her father he did not love her,  Peggy's romantic liaisons sometimes bring her short-term enjoyment, but the one long-term boyfriend she had ended up with a knife buried in his chest  and her swoon over Ted ended spectacularly; the marital failings of the Roger Sterlings and Don Drapers of the world are well known and need little comment.
So it came as no surprise that Pete had no problem bringing his new girlfriend Bonnie east to show her off at the office, but left her cooling her heels when he visited his daughter Tammy in Cos Cob. Sadly, his daughter barely recognizes him and recoils behind her nanny when he arrives (and who can blame her, that sport jacket would frighten young children). When his estranged wife shows up hours later (no doubt knowing he would have to wait until she returned home), Pete does what Pete does best - acts like an asshole - but Trudy was engaged in her own tit-for-tat and when he tried to moralize about her dating habits, buried him with the same caustic tongue that warned him about opening his fly within 50 miles of their home,  basically telling him he no longer matters in her (or their daughter's) life. So much for "family." That Bonnie does not like "New York Pete" is unsurprising, but the reality is that "California Pete" is not that different, save for the lengthening side burns and more casual office attire.
Meanwhile, Joan proves she's learned some lessons the hard way. Having (finally) tossed Greg out on his ear  and taken a pass at Roger's occasional flirtations, she was more than happy to have Bob around to give little Kevin presents or take a day trip to the beach, but when Bob pulls an engagement ring out of his (loud) sport jacket, she demurs. She'll wait for love and go solo because although the idea that we all need comfort in our lives, and particularly for those living through the turbulence of the late 1960s, she's unwilling to accept an "arrangement" with Bob, who she subtly "outs." 
The mood music, that is, the sturm und drang that propels the narrative, is familiar. A major account dangles in the balance, seats are being re-arranged around the table (Harry sure is getting paid back nicely for leaking word of the firm's pursuit of Phillip Morris to Don), and some reckoning is likely to occur, but beneath that, and where this show has always shined brightest, is in bonding the audience to the characters and the characters to one another. If you've invested seven seasons worth of viewing the trials and tribulations of these people, you couldn't help but swell a little at the sight of Peggy, Don, and Pete sharing burgers and sodas after all these years, all those battles, and all that heartache. The image of Don and Peggy slow dancing to Sinatra's My Way, its lyrics suggesting "the end is near" felt equal parts ominous and poignant. When Peggy softly put her head against Don's chest and he kissed her tenderly on the top of her head, it was hard not to think of a father and daughter sharing a wedding dance, but maybe it was just simply two people who long ago formed a familial bond that each had carelessly threw away and now hoped to get back.
2. Babylon, Season 1, Episode 6.
3. The New Girl, Season 2, Episode 5.
5. Shut the Door, Have a Seat, Season 3, Episode 13.
6. See generally, A Little Kiss, Season 5, Episode 1 and 2.
7. Lady Lazarus, Season 5, Episode 8.
8. The Other Woman, Season 5, Episode 11.
9. For Immediate Release, Season 6, Episode 6.
10. The Quality of Mercy, Season 6, Episode 12.
11. In Care Of, Season 6, Episode 13.
12. The Mountain King, Season 2, Episode 12.
15. The Better Half, Season 6, Episode 9.
16. The Collaborators, Season 6, Episode 3.
17. Mystery Date, Season 5, Episode 4.
18. The return of Bob Benson will surely please some, but this storyline had the feeling of nothing more than a throw away to close the Bob Benson "loop." The loss of Chevy's XP allows him to leave SC&P and go in house General Motors, never to be heard from again. Farewell, Bob.