We stayed at the Aria for a conference and enjoyed every minute of the 5 nights. The hotel rooms are super-sized, each with a corner view (because of how the hotel was designed), with a beautiful shower and separate tub and 2 sink vanity. The technology in the room makes is easy to work, play and shut down for the night - all at the touch of the button. The bed was incredibly comfortable (never quite like home, but pretty close) too. We were on floors 25-29, which are serviced by a separate bank of elevators - if you're there during a convention or conference, this is a huge bonus!
The service level from the hotel staff was unbelievable - very friendly, accommodating, prompt and knowledgeable.
The food in the resort is top notch - having eaten most meals at the conference and on site, we tested most of it.
The pool area is awesome - 3 separate pools with full service and towels etc. - a must for a visit to Vegas during the hottest temperatures on record!
Aria is in a great location, if you don't mind walking a bit - you can get to the tram that connects to Vdara and Bellagio in about 3 mins from the rooms - you can get to the strip through either Crystals or the Monte Carlo in about 10 mins...not bad at all for Vegas.
The casino at the Aria is a bit pricier than others, and if you're not a hard core gambler, they may deter you from gambling.
We would definitely stay here again if the price is right :).