You have a few options. Disney does not run any buses to Universal/IOA or to SeaWorld for obvious reasons. So...you can hire a towncar service, runs about $60 for a towncar which will hold 4. Various companies will be able to offer a larger vehicle for larger parties. Or you can check out the Mears site..they have a shuttle bus that you can reserve seats on for about $13-15 pp. But it has to be prearranged, so you could call the day before. Then, I believe they will stop at your resort to pick you up. But you don't get a lot of say as to when you leave in the morning or return to your resort.