If I went out in LV I'd definately visit the spot where I cut my teeth 10 years ago, Delmonicos, in the Venetian.
My cousin, who lives there, ate there in Jan and reported it's still top tier.
Bouchon is on the same property, and someplace worth checking out.
On the cheap, if you like Mexican food, check out a Roberto's. It's a local favorite, there's like 50 of 'em.
Ima sucker for the carne asada super nachos. I know, not very traditional... And not usually something I eat, but they are good here.