We will be arriving West Palm in the evening at 11:00. Will a booth at the airport be open or do we go directly via your bus to the lot?

+1 on any of the above answers.

Bus is the way.

You will have to take the bus to the lot. Even when the counter is open, you still wind up taking the bus to the lot on Belvedere to get the car.

Bus should take you to the lot.

Via bus to the lot