I would stay at either the MGM or Mandalay Bay. Both have massive pool complexes and lazy rivers. Mandalay also has the beach.
Assuming a group of friends are going with you, try to make sure someone stays at the Hard Rock because their pool would be great to hit too. MGM has more clubs in it than the others so you could easily end up never leaving the place. I prefer that end of the strip in general because I usually end of gambling at MGM, Mandalay Bay, and Luxor the most.
Don't feel compelled to do every little thing during that trip. The advantage of living in SD is you can always "scratch" your Vegas itch within a few short hours! You can go as often as you want later.
Hybrid Mode
