Melissa:
All of the
moderate and deluxe resorts have themed slides at their pools, including Old Man River at Port Orleans (best for the ages of your kids) and a pirate ship at Caribbean Beach Resort which would rank as my top two of the category. When our children were roughly the ages of yours, we stayed at Port Orleans and to this day, their best memory is of the pool.
For a considerable bit more money, consider looking at the Beach Club, the Polynesian or Wilderness Lodge for well-themed pools also for the ages of your kids. If money were not in the equation, the pool facilities at the
Beach Club score highest with my family because of the length of its slide, the unique sandy-bottom pool, the strong push current that creates a short "lazy river" experience and three whirlpools. It's so popular that Disney monitors the pool area to make sure that only resort guests have access.
Wishing y'all a magical vacation!
Whitney