Nice vowel progression puzzle. Was cruising along nicely and suddenly came upon 56A: Burma's first prime minister (UNU). Hah! I panicked briefly when I couldn't think of GUISE (49D: False front), and I put in "floor" for AISLE (63A: Most accessible seating choice), so everything was a mess down there for a while. Well, ok, probably ten or twenty seconds, but on Monday, those seconds add up!
I don't know about the disturbing sub-theme of the LUSTY (52D: Robust), SEDUCTIVE (11D: Alluring) FANTASIES (37D: Excursions to la-la land) about JIMPALMER's (34D: Orioles Hall-of-Fame pitcher who modeled Jockey underwear) DRESSCODE (4D: Casual Friday relaxes it), but, well… I SPOSE (53D: "Assuming it's true …," informally) I'll AVOID (33D: Steer clear of) comment on that.