Many of the rides have similar height requirements as the bigger parks, but this one has lower ones if they ride with an adult. Since we wouldn't let them go without an adult anyway, that worked great for us. Ian & Lynnea could ride everything, and Jadon & his friend, Ethan, were able to ride all but the roller coasters and one or two other rides. They could all ride all of the water rides. Most of the water rides have large rafts for 4 or 5 people, so that makes the slides more fun, too.
Some of the perks at Holiday World that you don't find at other parks include: free drinks (Pepsi products, gatorade, lemonade, etc.) all day long, a family-friendly atmosphere, very nice staff, free lifejacket use, and food prices that are similar to a McD's rather than jacked up prices found at most tourist places.
The one thing that we will do next time is plan a two day trip rather than one-a dry day and a wet day. There is way too much to do in one day, so we did miss some of the rides and didn't get to see the shows. It did help us that there were scattered thunderstorms all day, so the park wasn't busy and the lines were short. Longer lines would have made us miss out on even more of the rides.
If you are looking for a fun, safe, family-friendly vacation for your family, I would highly recommend trying it out. It's in southern Indiana, which is pretty centrally located for those east of the Mississippi.
