Spicey is right. There is no free shuttle to pick you up at the airport like with disney.
Last Nov I checked on the shuttle times at the resort and this was it :
The shuttle service is as follows :
7:55 am
9 am
11 am
12 noon
then pick up later in day :
4:30 pm
6 pm
8 pm
9 pm
and at park closing
The rate is $9/pp/roundtrip/day.
If you are a family of 4, that is $36 each day you visit the parks ! You can often get a rental car cheaper than that. At the very least, you can match that price for a rental and have full independence of the shuttle schedules. Of course, you'd have the parking fee at the parks, but that's nominal. The shuttle is free only if you are a renter....not an owner or exchanger.
There is only one place the shuttle picks you up and that is towards the front of the resort near the main lobby check-in. This is a very large resort and depending on where your room is, you could be either sort of close or quite far away and have a hike every day to the shuttle stop. I, personally, would never use it even if it was free. Due to the size of the Vistana resort, I feel a rental car is a huge asset and I wouldn't stay offsite without one.
Hope this helps
