Caesar's Palace is the best!! Really, you want to stick with a Harrah's property so you don't have to pay the silly resort fees (Caesar's, Rio, Harrah's, Bally's, Paris, Flamingo, and Imperial Palace). There's even a shuttle that loops between Harrah's and Rio and Bally's and Rio-- perfect for getting from the strip to the best buffet in Vegas (Rio's Carnival World Buffet!)
If you upgrade to a GO room at Flamingo, you'll be fine. However, if a pool is important to you-- DEFINITELY switch to Caesar's. Most gorgeous pool I've ever seen in my life! Caesar's has the best location, too!