We stayed at HRH in June 2006 and took one day to go over to Sea World.
Unfortunately, we got lost and it took almost one hour as we were way off course!!!
Getting back to HRH took less than 20 minutes. If you have a car, go ahead and drive over instead of using the shuttle bus - that way you decide the times to go and get back. Stop by the conceriege and get good directions first or invest in a good map!!!