If this helps anyone, this is the shuttle info for when we were at Bonnet Creek in April:
Transportation is provided by "Maingate Transportation"
Departures to Attractions:
MK & Epcot - every 30 minutes from 8 am to 12:30 pm, 2:45 pm, 4:45 pm, 5:45 pm, 6:45 pm, 7:45 pm, 8:45 pm (MK drop-off is to the TTC)
DHS & AK - every 30 minutes from 8:15 am to 12:15 pm, 3:30 pm, 5:30 pm, 6:30 pm, 7:30 pm
Downtown Disney - 3:30 pm, 5:30 pm, 7:30 pm, 9:30 pm, 11:45 pm
Returns from attractions:
MK - 12:15 pm, 3:00 pm, 5:00 pm, 6:00 pm, 7:00 pm, 8:00 pm, 9:00 pm, 10:00 pm, 10:45 pm, 11:30 pm, 12:30 am (returns are from the TTC)
Epcot - 3:15 pm, 5:15 pm, 6:15 pm, 7:15 pm, 8:15 pm, 9:15 pm, 10:15 pm
DSH - 4:00 pm, 6:00 pm, 7:00 pm, 8:00 pm, 9:00 pm, 10:00 pm, 10:45 pm
AK - 4:15 pm, 6:15 pm, 7:15 pm, 8:15 pm
Downtown Disney - 5:45 pm, 7:45 pm, 9:45 pm, 12:00 am
The schedule changes from week to week based on the park hours and expected crowds.
We never used the shuttle as we had a rental as well. I don't think I would like having the same bus for 2 parks though.