Totally depends on the type of experience you're looking for and the budget you're comfortable with. If I want upscale with the Vegas experience and some wow factor I'd consider the Cosmo, possibly with a terrace or balcony. If I want Vegas with more luxury I'd consider Wynn/Encore. If I want more luxury than Vegas, Mandarin Oriental or the Four Seasons. Purely Vegas with somewhat less luxury, Mandalay Bay, Bellagio, MGM, Caesar's, Mirage, etc., etc. Pool season, location, proximity to appealing dining are also considerations.