I think you can have a wonderful trip like that! If you decide to do the parks only one or two days, just make them really long days to get the most out of it.
The tickets are expensive, but maybe try to get them at a discount broker like Ticketmania or sign up for mousesavers.com newsletter which offers special ticket rates. This can help save you some money.
Plus, Orlando has so much to do besides Disney that you would never run out of options.
You could go resort hopping one day and have lunch or ice cream at one of the resorts. We just did this last week and had a great time. We wound up at the beach club near Epcot next to Stormalong bay and had a strawberry daquiri before dinner poolside. It was beautiful.
Check out FT. WIlderness and their little petting zoo which is free.
Downtown Disney is great to walk around and the kids would probably love the
Lego Store with all its toys and climbing structure outside. Also free.
Try minigolf one day.
Rent a boat on the lake.
Head to the beach one day. Daytona is about 45 minutes away to the east and Clearwater is about 1 1/2hours in the other direction on the gulf.
Check out Kennedy Space Center
So many things....so little time. So my vote is to go and have a terrific time!!!!
Hope this helps you.
HeatherC
HeatherC