well Kissimmee is pretty big 
If you are by the 192, there is a nice shopping complex with some good restaurants at Formosa Gardens. The Outback Steakhouse is one of our favouries as is the italian called Giordianos and there is a fairly good supermarket there (Marketplace).
Old Town, on the 192 (just West of Celebration) is worth a visit. On Friday and Saturday nights they have 'car night' where they have a lot of old and classic cars drive through and then park up and on Thursdays (I think) Its motorbikes if you or your DH like that kind of thing. Lots of nice shops and a few restaurants there and a few fun fair rides.
Good restaurants for fussy kids are Sizzler and Ponderosa, you'll find these along the 192 and some by I drive. They are 'eat all you can' buffet type restaurants and do pretty good breakfasts, we always fill up before going to the parks.
Our favourite shopping place is the Premium Outlet mall, just off the I4/SR535, lots of 'top' names and good prices.
Agree its nice to get down to a beach if you can, we went to Clearwater for the day last year and it was lovely