Which MGM is that?
TBH I have never been to Vegas as my destination other than for a conference. I am typically flying through LAS with one night -- but I do that a lot (3 times just this year). I've developed a routine. Here are a few things to check out:
Zuma at Cosmopolitan: absolutely top notch if you like modern cuisine with Asian influences.
Jaleo at Cosmopolitan: is a tapas place by Jose Andres Very solid.
Julian Serrano's Tapas at Aria: great tapas, might be better than Jaleo
Milos at Pallazo(?): Used to be at the Cosmopolitan. This is a Montreal seafood restaurant. The one in midtown Manhattan is one of my favorite restaurants. I ate at the Vegas location when it was at the Cosmopolitan. Highly recommend if you like seafood.
Street style: momofuku and teppa (sushi) both at the Cosmopolitan are very good.
Breakfast: Mon ami Gabi at Paris is great place. Also has legit classic French Brasserie style food
Desserts: there is a pastry place on the casino floor of Aria that is very good (don't remember the name).
North Las Vegas Mexican: if you're driving toward Utah (like I do) there is a great Mexican place called Viva Zapata.
https://goo.gl/maps/1PAdkQfTR6kvyBCLA
I would be interested if anyone has other recommendations.