I would also recommend pre-paid option when you book your car and make sure to confirm cancellation policy if you pre-paid. There are (sometimes) separate priority pickup lines so you don't have to wait in long general line for pickup. I was not aware of it and spent more than hour and a half at Budget rental at Sea-Tac location in Seattle.
You'll have to take a shuttle to the off-site car rental facility. It's about a five minute ride.
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