Best hotel: Cosmopolitan

I've stayed as high as the 66th floor. I recommend about the 30th floor. Too high a floor and it's like a helicopter view. The balconies overlooking the Bellagio fountains make the hotel the best by far and the rooms are on point. Pick the Boulevard Tower

Also, that part of the strip is live. You don't have to walk forever to get to the strip. The is an overhead walkway off the 2nd floor that take you over Harmon to City Center (where Aria is), another overhead walkway over the strip to Planet Hollywood/Miracle Mile Shops/Harmon Corner, and from there, another overhead walkway over Harmon.