The wife and I stayed in the Bellagio in 1/10 and loved it. We had a fountain view on the 18th floor. The hotel is upscale and really well managed. Our room was spacious and the bathroom was huge! The bed was soft, the comforter warm, and the walls were thick enough to provide a good amount of privacy (in contrast, see my review for Place d' Armes in New Orleans). We liked everything about it and would definitely stay here again. It was a top notch experience and as far as we are concerned it is the only place to stay.
My main complaint was the number of people who ignored the no smoking signs and were smoking in non-designated areas. There was a large number of foreigners in the hotel so maybe they did not read English or perhaps they are used to smoking wherever they want. The casino is a smoking area but it was not as bad as Ceasar's Palace which was by far the worst we visited in terms of number of people smoking and getting a headache from all the pollution.
The buffet is excellent. We had lunch there for $20 and breakfast for $15. It is so worth it. For lunch I was very impressed by the fact that the shrimp was fresh, cleaned, and firm. The various fish were moist and tender, not dried out at all. They had the best smoked salmon. For breakfast the variety is astounding, not just the usual. Had the best smoked trout and shrimp. I highly recommend this buffet even if you are not staying in the Bellagio. The lines were not that long, the most we waited was maybe 20 minutes when we went at noon for lunch.