I think Wynn is the best buffet in Vegas. Clean, gorgeous attractive room, wonderful selections and plenty big!
We didn't get to eat in the main room with the flowers but wow, that looked very nice. I also like how they list their main items on a board outside before you walk in to decide if its for you.
They had some really interesting items: Tandoori game hens, for one. It really hits on all of my criteria for a good buffet: clean, fresh looking food, interesting items, variety.
If you're thinking Caesar's or Bellagio for a dinner buffet, come to the Wynn. It's worth the trip up the strip a bit!