Can't go wrong with Skylofts....
I've stayed here quite a few times now (at least 6) and each time is as good, if not better, than the last. (Though I don't think anything will ever top my first time walking in and my jaw hitting the ground.)
Personalized service is the best part. They always know who I am, who I'm with, what I like and dislike, and have it waiting. I'm the world's pickiest person when it comes to having a soft and comfortable bed and I really appreciated their no-questions-asked approach to stacking about 5 duvets under the sheets in order to make it comfortable for me.
Skylofts elevators, Skylofts concierge, and private Skylofts entrance/exit (really, really, really handy when you don't want to wait in the 50-mile long MGM cab line) are the icing on the cake. Others have commented at length on the features and their quality, and that stands.
I wish they'd put Skylofts in the Encore - my Vegas dream team would be born :)