I'm so sorry that you were frozen at Disney World, but happy that you have a chance to come back!
There are probably going to be lots of opinions on which pool is the best and most relaxing, but one that you will hear about again and again is Stormalong Bay which is shared by Disney's Beach Club Resort & Disney's Yacht Club Resort.
Stormalong Bay is 3 acres big with 750,000 gallons of water! When my family saw it up close for the first time this past October I know we all stood there with our mouths hanging open for a good 5 minutes before running all willy nilly towards it! My kids said that this pool area is like a water park itself & they would have happily stayed at the pool for days without seeing another Park!
Stormalong Bay is actually a number of connected pools with sandy bottoms. There are whirlpools, a lazy river, a kiddie pool, waterfalls and shady areas. There is a shipwreck with a HUGE water slide. My family found a lovely little nook where I was able to sit & sketch while my kids had a great spot to swim near me that felt private. The relaxation factor at this pool is tops! I saw numerous LifeGuards on duty. This pool is so popular that the Cast Members make sure that you are a Guest at the Yacht or Beach Club Resorts and provide an armband for you.
I hope that you have a lovely & warm trip!