The M
https://www.themresort.com/dining/studiob.html
It's on the pricey side - $39.99 - but it is well worth it and includes beer & wine and my favorite, lobster
bisque. I would suggest going either a little earlier or later since the lines can get to be very long.
If you play slots/video poker go a couple of hours early and you can earn the buffet for 700 points on slots or 2000 points on Video Poker (and you keep the points).