Just went to the Signature this weekend and really enjoyed the whole experience. The hotel is a smoke free hotel and it is connected to the MGM through an indoor walk way.
Our room was on the 34th. It was a 2 Bedroom 3 Bath suit with full kitchen and balcony. The room was very nice and up to date.
The only reason I'm not giving them a 5 star is because they don't offer airport pick up and the hotel itself doesn't have any place to really eat. They just have a Starbuck and a little deli.
I will defiantly stay there again.