I always use Park n Cruise. Drive into their quanset hut, you and baggage unload without being out in the elements (great for rainy days or blistery hot days), they have limited bathrooms in there, but at least there's one there. Picnic tables out front in case you have a wait period for whatever reason. They do not park your car for you, but neither do parking garages. This place is just outside the port, it's the last exit off the 528, which is the route to get to the port anyway.