Don Draper has been off the rails for a few episodes now on “Mad Men.” He walked out of a meeting and just took off driving, first to look for a waitress with a sorrowful look in her eyes that seemed to speak to him, and then just out West, where he got beat up after a night out at the VFW and was last seen sitting on a park bench in the rural nowhere, having given his Cadillac away to a young con artist so he can begin life on a better start.

Don saw something familiar in him as well; he had, after all, taken somebody else’s name and built his life on a fraudulent premise in an industry that praises just that type of behavior. But now he had just had it and, in the parlance of the time, dropped out (though nobody used that phrase in the show).

By the time the highly anticipated finale began, he was out on the desert cranking up the speed on an experimental car — grist for those who still believed Don would turn out to be D.B. Cooper (a crazy notion based on the idea that every series since “Lost” has to have a big revealing explanation).

But no, it was just another momentary buzz, a stop to another sleazy motel room with another floozy who was just about to relieve him of all the rest of his money.

The fact that Betty had lung cancer — the one dark piece of poetic justice for a show that stood out from the first for its unabashed constant chain smoking — did provide the kind of emotional closing of a circle that I expected in the finale.

First he got the news from Sally, suddenly made mature and wise with the information (“Well, your mother’s a hypochondriac,” he replied at first before the stark diagnosis set him back). Then he called Betty for a hugely emotional, perfectly written scene: “Birdie,” he says between tears. “I know,” she answers).

I thought for sure he’d sober up, shave and fly back to New York to attend to all this and at least care for his kids, as he said he wanted to. And maybe that was his intention in continuing on to Los Angeles to catch a redeye.

But once in town, he looked up Stephanie, who has appeared on “Mad Men” from time to time as a person from his old life (“Hi Dick!” she greeted him). One of the times Don was out visiting, they even went on sort of a date until she put a stop to it (an episode I happened upon in the four day marathon that preceded the finale).

But since then, he’s tried to be a father figure, helping her out when as a hippie chick she was pregnant, Dropping in on her now, it was Don who needed the help — a couch and some chow, a shower and a shave — when he surprised her at her doorstep.

By now the child was gone and Stephanie was still searching — she was on her way to an Esalen-like retreat at Big Sur to sort these things out. Why wouldn’t Don like to come along? Normally, the Don we knew wouldn’t consider such a thing, but he was tapped out and maybe wanted to give her a ride.

The place was amusing both for its historical accuracy and to see it through Don’s eyes. All those annoying “how does that make you feel?” questions and odd characters — comedian Brett Gelman  of “Married” seems to have been cast particulary for his bushy beard. And that supremely weird confession by the guy who said he felt like the thing in the refrigerator that nobody picked — where did that story come from? Did it resonate with Don because it was a key piece of research about the human psyche? Did he see himself in the story? Was he feeling empathy for the first time?

Don was left behind at the retreat by Stephanie and was at his lowest spot, without booze to numb him. He called Peggy and had his most honest conversation yet. It was telling that all of the most emotional conversations in the finale were over the phone, foreshadowing a time when seemingly all important human contact was made over phones or the internet: Don with Sally, Don with Betty, now Don with Peggy.

All were long distance, hence the title for the finale, “Person to Person.”

But even the declarations of love between Peggy and Stan — even though they were in the same office — were done over the phone. (“What?” Peggy kept saying, as if they had a bad connection. Then after she made her own declarations, “Are you still there, Stan?”).

Their coupling was the one thing that rang the most false in the episode; they may have been longtime close colleagues, but to have this thing blurt out and be sealed in the final episode (after 11 p.m. yet!) seemed a bit too neat, especially considering Peggy’s history of romantic woes.

Watching so many “Mad Men” episodes this week in the marathon, it seemed the vignettes of the different characters and their summaries at the end was one of the rare weak storytelling moments for Matthew Weiner. As satisfying as it may have been for fans, it seemed to play a little too much in the expected TV finale playbook to see Pete and his reunited family starting his Lear Jet job; Roger in a Montreal cafe with Marie; Joan starting her new production company at home; Betty still smoking and sick at the table while Sally takes over homemaking.

And Don! What of Don? As difficult as it is to believe, he stays at the retreat center, learns a complicated yoga sitting move and …achieves enlightenment! He’s among the cliffside yoga class saying “Om!” and in one of those rare instances, making us realize how rare it’s actually been, he smiles.

To emphasize the humor of the moment, Weiner adds a ding! As if the roast is ready in the oven or a light bulb is going off. It’s a wink, and a smile, and it leads to what we are led to believe is Don’s next level of nirvana: the wisdom to create Coke’s “I’d Like to Teach the World to Sing” ad.

It’s funny and unexpected and brings a last minute happy ending to the series, which didn’t really need an ending at all: Survivors of the 60s, they roll into the 70s, becoming the Me Generation (which suits Don fine: to him, it’s been all bout Don along).

The Coke ad (which bizarrely was reprised in another Sunday night cable series, “Happyish,” as well)  also a last opportunity to show the tendency toward exacting detail in the show: One of the 1971 Coke singers, with red and blue ribbons in her braids, and a peasant blouse, is remade in the show as a cheery, non-helpful retreat leader who exchanges a few lines with Don.

So Don doesn’t drop out after all, but reaches the level of enlightenment to allow him to really make a killing at McCann and in the ad world. No more struggles for him.

It’s rather unlike anything else that’s happened in the rest of the series, but it’s a good last tip of the hat farewell to a cast and story that deserve it.