Outside of suites and upgrades at any place, Mandarin Hotel, THEHotel (Mandalay Bay), Cosmopolitan and Aria (two of the newest) are the best rooms on the strip. Mandarin and Cosmo are pretty centrally located next to Bellagio, Cosmo also has some of the hottest looking chicks hanging out all the time and some really amazing food places - Momofuko and Milk Bar are opening later this year, the pork buns in NYC Momo are to die for.
as long as its not a crazy convention weekend too the $20 trick usually works, just slip in a $20 bill (or $40 if you are staying like a week) when you check in and usually you will get upgraded, if there is no upgrade they'll just quietly slide your $20 back and you can die of shame in front of the line
Next to Planet Hollywood is the Hilton timeshare place, some people get lucky buying up timeshare slots on the cheap from people who can't make a trip at the last minute
in 2017 or 2018 Resort World is going to open, a massive new place opposite Wynn built by chinese money I think. Tons of themed places and stuff in there, and a few more places are scheduled after that. Also the Arena opens up next month next to New York New York, will have concerts and sports there and they are doing something behind MGM thats like a Rock concert park or something.