You mention Disneyworld in your question, but there are other parks in the area, every bit as good as the Disney parks.
Universal Orlando have two theme parks,
1) Universal Studios, which is TV and Film related
2) Islands of Adventure, which is an amazing theme park for all ages, with some great coasters.
These two parks are next to each other. More here
http://www.universalorlando.com/
Nearby is Wet and Wild, a water based parks with flumes etc.
A couple of miles away is Sea World (my favorite park) which is part zoo and part theme park, mostly based round sea animals (as you would expect from the name)
More here
http://www.seaworld.com/SWF/park_info_home.asp x
You can buy a combined ticket for these 4 parks which is less expensive than the Disney equivalent.
You can read more about the tickets prices here:
http://www.universalorlando.com/uk/tickets.htm l
Note the ticket page mentions Busch Gardens. While this is a great theme park it is a long drive from the main Orlando parks and with so much to do in that area it is not worth the drive to Busch Gardens.