My DD is 4, and very keen to do everything.
At Blizzard beach, we all went on the tabogan racers, DD had a life vest on, we all went down at the same time, the lifegaurd would keep a hold of her then let her go first, (so she could win).
This happened on all of the mat rides.
The tubes rides, she was allowed with me or DH, bit this will be harder if they is three of you.
There is also a area which is aimed at slightely older children, to go down the slides in this area i went down first and DD waited at the top and came down after me, and i was able to wait at the bottom to catch her.
I was also allowed near her when she was climbing over the ice berg things (sorry can not remember the names), basically you have to walk across the ice berg to the other side.
Hope this helps
Sorry can not speak about TL, not been there for a while we like BB too much