OK, my list, but it isn't very enlightening.
1. Best Breakfast Buffet
I don't go to buffets in Las Vegas. Stay away from Hotel Melon.
2. Best Dinner Buffet
See #1, except the part about the melon.
3. Best Late-Night
Noodle Asia at the Venetian.
4. Best Steakhouse
In all my trips to LV, I think I've had a grand total of one steak. With all that great food, why order something so boring as steak. Anyway, I had it at Delmonco (Venetian), and it was good, but big. And that was for lunch!
5. Best Misc.
I'm a big fan of Nobu (Hard Rock Cafe), but expect to pay $300+ for 2.