This is a first class hotel with a quiet atmosphere which is what you want when you are at the crazy busy Mandalay Bay. I was there for a conference and was so glad I chose this hotel instead of staying in the main hotel (which was a zoo).
The room was fantastic and they treated our toddler like he was a celebrity. The first night they even had a cookie with his name on the plate in M&M's which thrilled him to no end.
Everything was fantastic about this place - EXCEPT the concierge which was HORRIFICALLY bad! We came by at 7:00 PM and they already had a sign saying they were closed (in September during a busy conference with 100% occupancy). When I asked the front desk person (who was very helpful) about this he said they should be open and escorted me over there. He opened the back door to get the concierge and she yelled at him. He asked me to wait a moment and then later a man who appeared to be the manager tried to get her and she screams loud enough for the whole lobby to hear "I'M ON THE PHONE" with what seemed to be a social call as she was laughing a lot while talking. After a 30 minute wait she never showed up and I left. It really soured what was otherwise a fantastic hotel experience.
After our stay we switched to the Bellagio for the last part of our trip (planned - we just wanted to try two hotels). The Four Seasons took my wife and son to the Bellagio in a Black Mercedes S-Class like they were royalty which got them first class treatment there too.
I thought the Bellagio sucked after our Four Seasons experience so I'd stay there again, but I'd plan to do my research without the b*tchy concierge!