Originally Posted by
LabCat
No one has mentioned BWI's express lot, which is the way I always go. $10/day, pick up at your car by a shuttle as soon as you get out of your car, and closer than any of the off-site places. Plus, there is next to zero wait upon your return - there are always express lot shuttles driving past, whereas you could be waiting a while for shuttles for some of the other lots.
Sounds decent. I just booked preflight with a prepaid deal and it's about $7/day all in. Preflight is pretty decent; I'm not sure the BWI Express lot would be faster.