I haven't been to the new ARIA yet, but Encore is by far the best casino on the strip. It is classy looking, clean, and the watiresses come by often to serve you. They are faster with the drinks than any other casino I've been to in Vegas. They also have a lot more slot machines here than anywhere else. The restaurants are better. And the overall feel of the casino is just so "vegas". It gives the high end vegas feeling, not the low brow ghetto vegas feeling. I would spend the money and stay here. The club at Wynn is phenominal, check it out if you don't want to go to the newest Vegas hotspot.
Derek