Beds @ Skylofts at the MGM would have been my first choice. In fact, we own them in both FL and LV. Part has to do with the linens....Anachini Italian sheets....grab your ankles if you're considering buying them.
Subsequently, I'm thinking I like the Aria bed better but no luck on finding the original source.
For a standard room, the M beds are very nice as well.
I have stayed at Wynn, Venetian, Red Rock, Mirage, TI, Caesars, Monte Carlo, Eastside Cannery, Paris, Golden Nugget, THE hotel, Hard Rock, etc. I would take the Hard Rock's beds over anyplace I have ever stayed.
Best I've had is Mirage - very modern room; extremely comfortable bed. I've never had any problems at the RIO either; and SO QUIET and dark there for sleeping!!