I only know about the hotel restaurants, but I know a lot about them.
The best steakhouse in town is Craftsteak at MGM. There is no close second. Atmosphere is casual elegant. Wine is overpriced. Best vegetables anywhere.
N9ne steakhouse at The Palms has superb food, attentive if attitudinal service, a great and reasonable wine list, and a fun, noisy atmosphere with good people watching. Highly recommended.
Delmonico at Venetian has a wonderful creative menu and reasonable wine list. Service is spotty.
Nero's at Caesars is decent and has, as Craig said, a wine list with some very nice bargains (for Vegas anyway). Get the 2001 Stag's Leap Artemis Cabernet Sauvignon for $71.
I have eaten at Prime four times and have had horrible service three times and adequate service once. The butternut squash soup and the porterhouse are excellent. The room is beautiful. I do not recommend it.
Excalibur, Luxor, Bally's, and Circus Circus all have nice ordinary steakhouses where I have had good meals.
Les Artistes steakhouse at Paris is quite nice and not too overpriced. They have a good, unusual wine list and a great bone-in filet. I don't care for Mon Ami Gabi although you can't beat sitting out on the sidewalk overlooking the Bellagio fountains.
Kokomo's at the Mirage is very good but very noisy if the band is playing next door. It's a faux tropical rainforest atmosphere.
In short, it's not difficult to get good steak in Vegas, but while in town I would definitely visit Craftsteak or N9ne if you want a memorable experience.
QL