We're huge fans of the water parks, love 'em. Yes, BB has a more organized "kids" area, but honestly ages 7 and 8 are getting to the older end of that kids area. It's really meant for 8 and under.
Both of the parks are fantastic and have similar things, with different themes obviously. How adventurous are they? I don't recall the height restrictions on all the slides, but TL has roller coaster-ish water slides...instead of gravity giving you speed, you're propelled by a strong water jet pushing your tube. It's called Crush N Gusher. Tons of fun. The wave pool at TL is also like nothing you've seen. The waves are HUGE. Doesn't mean younger kids can't go in, but if they're not strong swimmers, keep them at knee level or less. The bottom of the wave pool is rough, so be careful. The shark reef at TL is also a lot of fun. BB wave pool is much more gentle, very small and frequent waves instead of one massive one. The two "big" slides are a lot of fun, but you WILL catch a little air. They both have really fun lazy rivers and plenty of smaller tube and mat slides.
Steps...lots of steps. Be prepared to climb them to get to the slides. BB has a ski lift style chair lift, but it has a long line and stops frequently, it's quicker to just walk. But you'll do plenty of climbing. The ground at either place can get pretty hot in the middle of summer. Some people wear water shoes. I personally can't stand them, so I don't. They do a decent job of watering down the pavement to keep it cool, but you'll encounter hot spots for sure...some quick tippy toe walking is required.
You'll have lots of fun at either, really.
