If you go to one of these restaurants you'd push past your 10 - 15 mile limit, however it might be worth it.
A lot of people rave about Shell's Seafood. There's one on Rte. 192 in Kissimmee (about 19 miles from DTD). And another one on Lee Road in Orlando (about 20 miles from DTD). I haven't been to either, but judging from the consistently positive things that some of my online friends say about Shell's I can't help but believe they're good.
I have, however, been to Straub's on East Colonial Drive in Orlando. This restaurant is also about 20 miles from DTD. And it doesn't look like much - either from the outside or the inside. I think of it as a restaurant for locals as opposed to all of those in the touristy parts of Orlando that serve us vacationers. The servings are BIG and good is great. I highly recommend Straub's if you're willing to stray a bit more from the Mouse.
Dick Taylor