I've stayed at Bellagio a few times so far and I must say that the experiences have been great. The rooms are nice and the view of the fountains with the matched music playing on the TV made it a pleasure to just sit in the room.
The staff is very nice and are quit accommodating to your every need, even throwing in a few extras here and there. The gym was great and much larger than I expected. The pool area is large and luxurious. Lots of space to swim and hang out without feeling crowded by other people.
My only complaint is the lack of a mini fridge. They give you a pressure sensitive automatically charging mini bar that I have no interest in using. At least offer an empty fridge as an option for additional convenience. But I won't let that knock off a star because the rest of my experiences there have been wonderful.