I was always a huge fan of Bellagio, but I stayed last June and rooms were getting aged. I heard they have remodeled, but I'm sure room quality is still not compareable to Encore or Aria. Bellagio also doesn't have a day pool party spot like Aria (liquid) and Encore (beach club) For a nice laid out, fun casino Bellagio is great. My favorite place to play poker is The Wynn because of the hot girls walking by the rail and the cool staff. Aria has my new fav restaurant Jean Georges. Never been a big fan of Venetian either
His remit specifically said must have casino and poker room. When we get to the point where we are measuring corridor length to work out if a room close to the elevator in Encore is closer to the Wynn poker room than a room in the Wynn at the far end of the corridor, or if route A is covered while route B is uncovered but 200 yards shorter, it's probably gone a bit too far.
If you need a casino because of your comp action, then I understand staying in that hotel. Otherwise, they are all a trivial walk to anyone not in dreadful health.