One ride that's fun and not rough is Teamboat Springs at Blizzard Beach. The raft is large-last time it carried 5 adult women (and only 1 is petite) and one small DD6. Our butts were dragging at the start but then it was fine-and definitely not rough, very smooth. We love it.
Oh I'm so jealous, I just noticed you're going tomorrow! I can't want til we're one day away but were not going until Sept. Have a great time.