I've stayed at Mandalay Bay a majority of the times I've ever been to Las Vegas. It is getting a bit old, though. The hotel could definitely use a little refreshing, but I think it's still a beautiful place. I always go to the wave pool whenever I stay at this hotel. The exterior always looks gorgeous. I also always go to the buffet, and I think the quality of food is better than the Bellagio's buffet even though there isn't as much of a variety.
They removed the giant fish tank that was in their check-in lobby :( so now there are just a bunch of seats laying around. I don't really mind that this hotel's relatively far from the strip, but for those who do mind, this hotel's probably not the choice for you. At least there's the tram to bring you to the Excalibur (closer to the strip).