Your kids are older, so I'm keeping that in mind when I give you my recommendations.
Definitely a waterpark is worth considering. Aquatica is our favorite of all of them in Orlando, hands down. It was our son's #1 choice when he was an older teen/young adult.
Mini golf was also always a family favorite. Congo River takes top spot for us, but we have also golfed Pirates Cove, the two courses at Universal Citywalk, Hawaiian Rumble, Gator Golf, and Lost Caverns. The two latter that I mentioned are currently deeply discounted on Groupon, if you're looking to save a little $$.
Madame Tussauds Wax Museum is GREAT for self-loving teens. Combine that attraction with a ride on the Wheel for a nice afternoon out.
Gatorland is a great half day attraction. Even better, consider the Gatorland Night Shine tour.....you get to go into the swamp, after dark, with nothing but flashlights and a big bucket of gator chow, and feed the alligators as their eyeballs glow orange. You also have the chance to meet and hold a bunch of other Gatorland creatures......we got some incredible photos holding massive snakes, a tarantula, a giant skink, and more. At about $20 a person, it made for one of our favorite nights out on our last vacation.
An airboat tour is also a ton of fun. We have done Wild Willy's and Wild Florida, and enjoyed both very much.
The monster truck tour at Showcase of Citrus is a good outing, especially when you top it off with one of their fresh orange slushies after your ride. Soooo yummy!
We rented a pair of jet skis one trip (with the size of your group, you'd obviously need more than 2), and spent a couple of ours zipping around Lake Minneola and Lake Minnehaha in Clermont. The skis seat 2 each, and we had an absolute blast. The scenery was stunning.
We did a helicopter tour one trip, and it too was a great memory maker. Our flight was over the Kissimmee area and it was an incredible experience to see the area from a whole new vantage point.
We have also done Wonderworks and it was 'okay' but there are better places to spend money, IMHO. Ripley's was a disappointment. Sea Life Aquarium was good, but may not be of interest to your older teens. There are a couple of chocolate museums in the area (we have done both) which are worth it if you can get deeply discounted admission (check Groupon for those, too).
A visit to Disney Springs can be a lovely way to spend a few hours. Have a drink on the rooftop bar at the Coke Store, and splurge on cupcakes from Sprinkles or cookies from Gideons. Go for a ride on the Characters in Flight balloon, and browse some of the shops.
