I've eaten at Rosemary's and enjoyed it very much, and I've eaten at other great restaurants in Las Vegas and enjoyed them very much, too.
But sometimes I want a buffet. They're fun. They're exotic. They're a Vegas institution. They've got incredible variety (mediocre food sometimes, but an incredible variety nonetheless). And they're a place where I can stuff myself silly.
Good food is a very good reason to pick a restaurant to eat at. But it's not the only reason.
Perhaps a good strategy is to go to the good buffets, but go at breakfast or lunch instead of dinner. A fun time can be had by all for less money, and then you'll be able to visit a wonderful restaurant for dinner.
We (my wife and I) enjoy the Paris buffet for breakfast and lunch; I suppose dinner would be enjoyable, too.
Mandalay Bay is good but nothing to write home about.
Bellagio is a spectacle to see and walk through, though we haven't returned since our first visit to it. It wasn't bad, it was just not as good as other buffets we prefer to visit.
The new buffet at Mirage has good tasting food, though the selection of items is smaller than other buffets we've eaten at.
We feel that the Rio is over-rated. It has a huge selection of items, though nothing was really outstanding. They seem to be riding their laurels from when they were the bees-knees of buffets 10 or 20 years ago.
The Aladdin buffet was enjoyable for lunch (and seems to get higher-than-average ratings from internet-rating buffet-eaters), but it's hard to know if it's still that way with their big switch-over from the Aladdin to the Planet Hollywood hotel/casino.
IMHO-the dinner buffets in Vegas worth going to are so expensive that you could do like christies sugested, or go to Emeril's at MGM, or any number of places and have some of the best food in the world for about the same or maybe $20-$30 pp more at many of Vegas' best restaurants. What's $20 when you're in Vegas?
I agree about Wynn, Paris and Bellagio. I recently enjoyed the lunch buffet at Treasure Island. It included several types of sushi, sushi rolls, made to order salads, etc. It was just very fresh, short lines at each station and a very upscale seating area. It's also pretty inexpensive, especially compared to Wynn and Bellagio.
Avoid the buffets and grab a $20 taxi ride to Rosemary's on West Sahara. All menu items can be ordered either ala carte or flexed into a tasting menu. By far the best meal I had in Vegas, hands down. Otherwise don't do any buffets without a coupon, they suck and are totaly overpriced. quality is much better than quanity.Coupons can be found on the net or by signing for the casinos player cards, many of them offer fun books or coupons.