We used to go to both water parks when the kids were younger (adults now!). Son #3 is special needs and has very fair skin. So we would get there when the park opened, and we would head for the family rift ride from the top. (for this ride, BB has the longer family raft slide). Then DH would take #3 to the lazy river while I rode the big slides (and snorkelled) with the other kids. We would meet up for lunch, and shortly afterwards I would leave with son #3, who was tired by this time. Then DH would head for the slides, wave pool, etc with the other kids.
I offer this plan as it works for families with big kids and little kids as well. When they were a bit younger, we did spend lots of time in the kids section, and the 7-10 year olds loved the section at BB with the ice boulders, etc. (When #3 was small enough to be carried easily up the mountains, we did more slides with him).
So we DID stay all day at the water parks, just maybe not all 6 of us. Other days we may have left at 3-4 and gone to DD at night. We had the old 5+2 tickets then, 5 park hoppers with 2 water parks.