Buffets: no on Aladdin. yes on Paris and Bellagio. qualified yes on Rio. Paris coffe shop and Mon Ami Gaby at Paris are good.
Museums. No on Bellagio art (a couple of dozen masterpieces from a wide variety of periods) the only thing that makes it Vegasy is that all the paintings are for sale. Yes on the wax museum - because there are no ropes or barriers around the mannequins, you can have your photo taken next to famous images. Yes on the Imperial Palace Car Collection, if you like cars. For pure, uncut kitsch, the Liberace Museum (well off the Strip on E. Tropicana Ave.). Yes on Gambling Museum at Tropicana (lots of Las Vegas history). No on the Elvis-A-Rama collection, but qualified yes on the Elvis-A-Rama gift shop (includes things not for sale at Graceland).
Shows. Hell-no on Siegfried and Roy. Yes on Penn and Teller. Yes on Amazing Jonathon (an acquired taste). Hell-yes on <<O>> and yes on "Mystere" Yes on Lance Burton (his sleight of hand is the tops).
Attractions: Yes, for fountain, volcano, pirate show, NYNY rollercoaster. No on Eiffel Tower (viewing platform is way too small). Yes on Stratosphere Tower, but only on weekdays (yes on the thrill ride (if you are brave enough) no on their rollercoaster). Yes on Main Street Experience if you have time for downtown. No on Siegfried and Roy's Secret Garden, yes on the white tiger display at the south entrance to Mirage. If you have a car, yes on Gambler's General Store. Yes on Red Rock Canyon. Qualified yes on Star Trek experience.
Lastly, it is exceptionally hard to sneak into the pool area at Hard Rock, but it is well worth the effort.
You'll find more info in the alt.vacation.las-vegas newsgroup