Actually, the trolley route continues south of Sea World to the Premium Outlet Mall. The I-Ride Trolley is a great way to get around and very reasonably priced (especially when compared to the expensive taxis and nearly non-existant city buses).
You could start with iridetrolley.com and look at their maps, to get a feel for which hotels are located where, and where you might like to stay. There are two trolley routes, one goes up the main I-Drive and one up Universal Blvd., which runs parralel. Universal Blvd. is only one block off of I-Drive, but it's much quieter. I've stayed in the Rosen hotels at either end of the convention center, and they were nice. I've also stayed at the Wyndham at the corner of Sand Lake and I-Drive. It was OK. I've heard good things about the Doubletree Castle, although I haven't stayed there myself. There are restaurants all up and down I-Drive between Sand Lake and the Convention Center, within walking distance (or use the trolley and save your feet for the parks!). I like Ming Court (just opposite Pointe Orlando) and Bahama Breeze the best.