I just call my hotel. The shuttle to US is rather late as Robvia said. Anyway, I'll be driving to IoA early in the morning since I want to take my family back to MK in the mid-afternoon. While for US, I'll stay there for a whole day on a weekday next week near the end of my trip. So taking the hotel shuttle would be fine. It is interesting that the shuttle at my hotel going to the Disney departs a lot earlier and has 2 rounds. I guess it is the same bus going to Disney theme parks 2 rounds before going to US. 
