Glad you're coming down! The two parks are quite different; the only coaster they both have is Batman, and ours is a mirror image of the one in Chicago, so it even feels a bit different.
I haven't been on Justice League in Chicago, but I would expect it's identical and therefore skippable. I would also recommend skipping Boomerang and Ninja. They're just not good, and your time is better spent on other rides.
I wouldn't expect huge crowds that weekend. The waterpark is a big draw, so attendance is low until it opens. If crowds are larger than usual, get a Flash Pass; otherwise, don't worry.
I tell people to start with American Thunder and work your way around clockwise. That puts some of the lower capacity rides like American Thunder and Pandemonium early in your day.
As for flats, if you like spinning or flipping rides, don't miss Excalibur. It's a nearly unique flat. Sky Screamer is really good too. Don't worry if Superman is down; Great America's drop tower is better (and ours is down a lot).
Have fun!
Thanks! I'll probably ride Batman to get the credit. I've been on 2 BTR clones and they are pretty worth the credit! I'll just skip JL; No need for it as it isn't a credit haha. I have been on one Boomerang (SFFT) and I loved it, so I won't skip the Boomerang there. I might skip ninja depending on time. Thanks for the advice