If you like steaks, Charley's is an excellent choice. Two locations on I-Drive. cozy atmosphere, fine dining, outrageous steaks, great service, and great wine.
Our one must-do-every-trip restaurant is Columbia in Celebration. It is different -- old-line, authentic Spanish cuisine from the historic Ybor City area of Tampa. Nice, up-scale ambiance, gracious service. Their "Legendary 1905 Salad," which is mixed at your table is truly legendary. I've had numerous dishes there over the years and never, ever had anything that wasn't wonderful. My new all-time fave, since our Dec visit, is the "Grouper Jimmy."
I would also second the suggestions of Texas de Brazil and Seasons 52 -- although both may be more crowded, less quiet, than you are looking for. Both offer wonderful food, but are usually crowded and noisy.