absolutelyflawed - in the past we have often worn swimmers to go on the big water rides - swim shorts and a t shirt for me and DH; DD wears a swim vest or bikini top with swim shorts. On some you do get completely drenched - imagine how wet you get in a shower, its like that. Literally like someone has tipped a bucket of water all over you, and a big one at that!
This last visit only Dh and Dd did the wet rides - I don't really like getting wet! They has normal day clothes on this time (though DD took her pants, bra ad t shirt off and rode just wearing shorts and a vest top instead - she then replaced the pants (she hates wet pants!) and her bra/t shirt and took the wet vest off. They did get drenched. Because the weather wasn't as hot as it is in August it took much longer to dry! However, they did dry off a bit and we were staying on site so not too bad.
Some of the water rides get you much wetter than others.
The worst are Kali Rapids at Animal Kingdom, Popeye and Bluto's Bilge-Rat Barges, and Dudley Do-Right's Ripsaw Falls at Universal's Islands of Adventure.
There is also Jurassic Park River Adventure at Islands of Adventure and Splash Mountain at Magic Kingdom - you get less wet on these but depending on how it hits you it can be a decent amount. Though sometimes you get away without too much water splashes!
The ride I got wet on this time was the innocuous looking One Fish Two Fish at Islands of Adventure - think DD was timing going under the water sprays far too accurately for my liking.
When DD was little we always took swimmers - there are lots of water play areas...
... Curious George at Universal Studios
... If I ran the zoo at Islands of Adventure
... Mystic Fountain at Islands of Adventure
Plus there are fountains at most of the Universal and Disney parks. If they are anything like DD was your children will get soaked!