I found it interesting that this episode opened with Betty and Don dealing with pesky mother-in-law issues.
Don's literally speaks a different language than his, though Megan's mere is probably no match for the malevolent Mama Francis, who clearly enjoys manipulating the heck out of the daughter-in-law she can't stand. Don and Betty also both face the irritation of having to do things with their new spouses that they don't want to, whether it's a trip to Fire Island or a Junior League gala.
These bits of family discord seemed in keeping with this episode's focus on the generation gap, and the culture clash between them. For me, Don and Harry's trip backstage at the Rolling Stones concert was the centerpiece of this episode, more so than even Betty's big (really big) reveal and the health scare that proves to be her wakeup call. Jon Hamm gets major props for nice touches in his directing debut on "Tea Leaves," penned by Erin Levy and Matthew Weiner.
Don and Harry go through the looking glass to a netherworld of young (like not that much older than Sally young) girls smoking joints out in the open and openly plotting to give themselves up with abandon to the cute English rock star of their dreams.
The girls put Don and Harry in their place, comparing them to the caricature of "Bewitched," and scoffing at the notion of their anti-establishment heroes doing a mere "TV ad." Harry is much more than comic relief (and at that he is wonderful) in this sequence.
The age difference between him and Don is evident in that he goes for the joint and is enamored of the whole scene. Even if he is still bumbling Harry Crane who can't tell the difference between the warmup act and the real Rolling Stones. The bumbler who can't tell when he's digging himself a deeper hole with the boss. (Don seems fairly disgusted by Harry's appetite, and not just his taste for White Castle.)
Ever the scheming ad man, Don can't help but ask his Ms. Flirtatious how listening to the Stones makes her "feel," and he's a little startled by the answer. Not only is it sexually frank about wanting to "jump on Brian Jones like Jack Ruby" but it's also sarcastic about an world-shaking tragedy that is only about two and a half years removed from the time frame of this seg.
Don is so startled he can't take the bait when she takes off his tie (Don of season three or before would have had her in the hallway in a split second.) The girl is taken aback too, which is why she gives him the zinger: "None of you want any of us to have a good time just because you never did." Don responds, honestly, as a father more than a libido: "No, we're worried about you."