I have stayed at the Vdara twice and have found it a wonderful place to stay while in Las Vegas. It is not your typical Las Vegas strip hotel in that there is no casino.
This means a couple of things: 1) you can keep more of your hard earned money and 2) there won't be a ton of random people walking through the hotel which makes getting cab at night easier.
It's location in City Center is ideal if you like shopping. And it's close proximity to The Bellagio and Cosmopolitan put you right next to a couple of great hotel/casino situations.
The rooms are well appointed, albeit a bit dark at night. The staff are always helpful and friendly with additional security by the elevators. I've had nothing but great experiences in this hotel.