Although Bellagio has recently made some upgrades, for a vegas visitor looking to enjoy a posh poker room experience, Aria is it tough to beat.
The dealers are great, there is always a decent game selection and cocktail service is quick and attentive. If you want to step away from the tables there is also a a great pizza place a few steps away and a decent sports bar area.
Only downside is that room itself requires a little effort to find and get to - but that's pretty standard with anything in a big Strip hotel casino.