Things rarely turn out well for Don in California  and when he and Roger head out to fish for some new business, Don has a hashish-fueled hallucination that suggests his vision of life and death is every bit as grim as ethereal "footprints in the sand."  The birth/death imagery is thick - Megan is transformed into a long-hair-flowing hippie incubating his love child while Private Dinkins, his drinking buddy from Hawaii, is a wraith, observing that "dying doesn't make you whole, you should see yourself" as we jump cut to an image of Don face down in a pool of water.
Indeed, Don and Roger's "Ocean's Eleven" trip was notable more for the dissonant strains of psychedelia that were juxtaposed against their unmoving Rat Pack-era insouciance, but glib pitching to Carnation was no more successful than Roger's attempt to lift flower child "Lotus" from the grasp of former copywriter (and in-law by marriage) Danny Siegel, who reinvented himself as a Hollywood producer (or a pint sized Dennis Hopper circa Easy Rider).
Don and Roger's lost week ends on a dour note, each spent as they jet back east, but their conversation on the plane echoed one they had years before in a dimly lit bar after bidding fare thee well to Freddy Rumsen as he was sent to rehab and advertising purgatory. There, it was Don, just having been kicked out of the Draper family home, dispensing one of his patented bromides about how you only live once, that you have to move forward in life as soon as you what direction that is.  Now, it is Roger's turn to share some of his wisdom. He tells Don that his therapist has explained to Roger "the job of your life is to know yourself." This is only the latest variation on the same theme - "who is Don Draper?"  - but the question is left dangling, or more specifically, asked and answered, because Don is no more interested in introspection or self-discovery (much less self-analysis) than he is in fidelity.
Back at the ranch, palace intrigue is the order of the day and Joan, burdened by the weight of her (perceived to be) ill-gotten partnership attempts to secure a client all on her own. A tip from her friend Kate, who we met earlier this season , leads Joan to Andy Hayes, the Director of Marketing at Avon. In a scene reminiscent of Lane's lucky break meeting with fellow ex-pat (and Jaguar executive) Edwin at a pub while watching the 1966 World Cup game between Great Britain and Germany , Joan wants to keep the account all for herself, even after Ted advises her otherwise. Like Lane (but without Roger's glib advice), Joan decides to try and secure the account, bringing Peggy into her ruse, but failing to close the deal. When her chicanery is exposed, Pete lashes out at her, but Peggy's quick thinking (a bogus phone message that Avon is on the phone) rescues Joan from more verbal abuse.
Here we got to see a couple of threads tied together nicely. After all, way back in Season 2, Joan took on the task of poring over television scripts to ensure they did not run afoul of the advertising the firm was doing on behalf of its clients. Harry Crane, as clueless than as he is lecherous now, missed her contribution entirely, hiring an underling to take her job, leaving her crestfallen.  Meanwhile, it took leaving SCDP for Peggy to receive the professional recognition she had long desired. 
That each character symbolizes the treacherous waters women had to navigate in the workplace in a bygone era has long been established, but Peggy and Joan have sometimes worked together and other times at cross purposes. In this way, they don't resemble rivals so much as sisters, clearly connected and fond of one another, but also invested in nursing grudges or emphasizing the things the other has that each wants. Joan's job is to think of things before people need them, but she can't quantify that value because everything she does in the office is tainted by how she acquired her position there, a knife Peggy twists when Joan questions her rise as a copywriter by reminding Joan that she (Peggy) didn't sleep with Don to get to where she is.
On the other hand, Peggy is not an executive, and is therefore left out of the decision making process in the office. She can lobby for her ideas or pitch clients, but ultimately, a cross word can get her kicked off an account  and the clients she does secure can keep asking her to prime the pump to come up with ideas for them to consider.  On top of all this, Peggy is now caught between Ted and Don's egos (not to mention Roger, Jim and Pete) without a voice in the management of the firm. Instead, she is left to her wits to collect office intelligence and look out for Joan. But their bond, while complicated, is clear.
Not so the machinations of Jim Cutler, who takes advantage of Don and Roger's absence to poach the loyalties of the enigmatic Bob Benson in lieu of cleaning house of the SCDP creatives that populate the large work area on the main floor of the firm's office. While Ted is trying to get Jim to sing "Kumbaya," there is a reckoning coming as the "us versus them" mentality appears untenable in what is now termed Sterling Cooper & Partners. Jim does not care about the loss of Manischewitz (a "Roger" client) and is eager to insert Bob into the bloodstream of the GM account, throwing the other partners the bone of a name change that highlights Roger and Bert's prominence while collecting what he thinks are chits that will help him marshal power in the new firm.
And so it goes. A Tale of Two Cities was really a story of three, because while there was a mirroring of effort in New York and Los Angeles to gain clients, the mood music in the background was the rioting at the Democratic National Convention in Chicago, a thick cloud of marijuana, ever shortening hemlines and technicolor wardrobes that are now in full flower. Even Pete Campbell realized he had to tune in and turn on (dropping out is likely out of the question).
1. Don escapes to California during Season 2 after Betty kicks him out of the house. The Jet Set (Season 2, Episode 11) and The Mountain King (Season 2, Episode 12). He visits Anna at the beginning of Season 4 only to find out she has cancer. The Good News, Season 4, Episode 4.
2. The Doorway Part II, Season 6, Episode 2.
3. The direct quote is: "It's your life. You don't know how long it's gonna last, but you know it has a bad ending. You've got to move forward, as soon as you figure out what that means." Six Month Leave, Season 2, Episode 9.
4. Public Relations, Season 4, Episode 1. Other nods to Don's enigmatic qualities are legion, but two examples from Season 6 are emblematic. In the season opener, a photographer tells Don to "be yourself." The Doorway Part II, supra. At dinner with Arlene and Mel, Arlene observes that Don is a man who "plays many roles." To Have and To Hold, Season 6, Episode 4.
5. To Have and To Hold, supra.
6. Signal 30, Season 5, Episode 5.
7. A Night to Remember, Season 2, Episode 8.
8. The Other Woman, Season 5, Episode 11.
9. In Season 5, Peggy attempted to muscle Raymond Geiger from Heinz into signing off on one of her pitches. He was offended at her assertiveness and had Peggy kicked off the account. Far Away Places, Season 5, Episode 6.
10. The men at Topaz Pantyhose just assume Peggy can continue offering ideas ad nauseum when Peggy and Ken meet with them. Tomorrowland, Season 4, Episode 13.