Finally got around to seeing this today, and yeah, it's pretty damned classic. Laundry list!:
-My favorite performers are easily Harvey Korman ("Why am I asking you?") and Gene Wilder with his perfect deadpan, although Dom DeLuise does indeed kill as the director of "The French Mistake", and Madeline Kahn's mix of sexiness and humor is dearly missed. I was also pleasantly surprised by how great Slim Pickens was, as it's completely different from his equally funny work in Dr. Strangelove (did we ever get confirmation that Kubrick didn't tell him it was a comedy?).
-While Richard Pryor probably would've been great as Bart, I like Cleavon Little's work too much to replace him. Bart functions as something of a straight man for much of the film, after all, and Cleavon balances that excellently with Bart's rarer lunatic moments (the amazing hostage situation, "Candygram for Mongo!" and "Where de white women at?").
-I actually enjoyed the Looney Tunes lunacy of the finale, although it is perhaps weaker than the rest of the film. I think the reason Young Frankenstein ultimately wins out over Saddles is because it actually has an honest-to-God heart and sweetness to it, and it does feel more "complete" as a screenplay. But Saddles still has a great, breezy, ramshackle charm to it.