Or how about one of the hotels on IDrive? Quality Inn International for example does have shuttles on offer but i think you have to pay and they are limiting when you may want to stay longer. But you could jump on the Trolley Bus outside the hotel and get to the bus stop at Seaworld in around 20 minutes or less depending on traffic; hop off one stop before Seaworld and catch a lynx bus across the road to Disney; and go the other way up IDrive for Universal. Its a 20ish minute walk into Universal from the bus stop along a straight pathway (can't get lost) although a couple of the roads are very busy when trying to cross and waiting for the walk sign to show up seems like forever.
