Connie:
Blizzard Beach and
Typhoon Lagoon both have plenty to offer the younger set. However, when I had my choice when my kids were the ages of yours, we tended to head to Blizzard Beach.
Because our favorite slide at Typhoon Lagoon (Crush 'n' Gusher) required you to be 48 inches, I usually had to stay back with one or two of the children so the older ones could go. Additionally, Typhoon Lagoon's wave pool was too strong for not only me but my younger swimmers who, like yours, were not particularly experienced, so over time, we tended to opt more for Blizzard Beach. There, we found its pre-teen Skip Patrol Training Camp full of adventures, the family raft slide actually longer than TL's, a fun chair lift to get you there, and a large pool area that was more our speed. If you have to make a choice, Blizzard Beach would get my vote.
Wishing y'all a magical vacation!
Whitney