I'm not sure I'm understanding your post. Are you looking for non theme park activities or are you open to doing theme parks?
Orlando, of course, is the them park capital of the world. Have you been to the parks down there other than Universal? It sounded like maybe no. If not, do note that SeaWorld and the Disney parks are enjoyed by people of all ages and aren't just for little kids. Parents go with their teens, adults go by themselves to these all the time (A woman who I work with whose kids are grown goes down almost annually usually every other year -- one year just she and her husband and the other the two of them plus their 20 something kids.). My 19 year old son loves SeaWorld (his favorite park in the area) and all of the Disney parks (the traditional Magic Kingdom park is probably his favorite of those). I love the parks too, so if it were me (even though it's expensive), I'd do SeaWorld one of the days and one of the four Disney parks on the other if you and your son are interested.
SeaWorld is a beautiful park with world class animal exhibits and shows. It has two coaters, a water ride, a simulation ride, etc. too. It's a different feel than Disney and Universal, more relaxing. (I agree with Brian and Gina that this could be a great option for you.)
Also, at least for me and my 19 year old (some people just aren't into theme parks, like my husband), there is just something Magical too about walking down the middle of Main Street USA at the Magic Kingdom and spending some time there doing some of the attractions. Actually I get a great vibe and enjoy any of the four Disney parks. That's why I'd spend a day at one of those too.
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If theme parks aren't your thing, aren't in your budget, and/or you don't have an interest in doing the parks this time:
We like the Titanic attraction on I-drive. Very well done -- takes about two hours.
And across from Wet and Wild on I-drive, there is an indoor wind tunnel where you can have a safe indoor sky diving experience in a wind tunnel. It's called I fly. They get an interesting mix of ski diving teams honing their skills and tourists. Our extended family group ages 13 thru late 70s all did it one year. You get a one hour instruction class and then each person in your group gets their turn in the wind tunnel with an instructor right there with you the whole time. Each person gets two turns and you get way for air time than real sky diving.
And if you like waterparks and weather is good for that, there are four great ones to choose from: Disney's Blizzard Beach, Disney's Typhoon Lagoon, Wet and Wild, and Aquatica. If you do SeaWorld there is usually good pricing on a SeaWorld/Aquatica combo ticket and you could do one each day. That could be an attractive combination for you, and you could even stay in one of the hotels over by SeaWorld. I really like the Hilton Garden Inn SeaWorld and you can walk to the parks or take their shuttle. All the other hotels around there get good reviews too.
Gatorland is an old time Florida attraction in the area too vs. a world class theme park, a half day place. When we go we usually spend about three hours there. My husband likes it because it centers on alligators that are native to the area vs. man made things theme parks have. It's a little tacky, but fun and we've visited multiple times over the years: snakes to hold, alligators jumping for frozen chickens that have been thawed out, alligator wrestling shows, etc.
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