I've been 3 times and the 'so-called' economy lot has been full each time. I think $20 is too expensive for Snohomish County Airport, so I really don't like having to pay $30 because the cheaper lot is full. You can find parking at SeaTac that is much cheaper than that, even the Port of Seattle lot can usually be had for around $20 with the coupon. Also, the P4 lot seems like an after-thought and not well designed. But, aside from the parking rip off the terminal itself is wonderful, and very low stress compared to SeaTac.