Previous years in Las Vegas I have had the pleasure of staying at The Venetian. Full disclosure requires that I admit that these visits were on my employers dime, so I cannot speak to the price/value but I can certainly say I prefer the rooms at the Venetian.
Having said that, Mandalay Bay offers many fine things. the Parking seems easy to access, and the ability to get on the Tram is also a very nice touch.
There are several rather nice restaurants, but most seem slightly out of my price range for an average afternoon or evening meal.
The pools are amazing, but I can only speak to this from a visual inspection, and the words of friends. I have never personally taken advantage of them.
Finally, the walk from the room to the convention center seems a bit extreme, coming out to almost 3/4 of a mile from room to center. I guess that's so you can work off all the food you can't afford!