If I just show up at the SuperShuttle counter at BWI and buy a ticket, how long is the wait before the shuttle comes? I've always pre-purchased my ticket online and checked in at the counter, but there's still a 30- to 40-minute wait. For an upcoming trip, I won't know exactly where in the BWI area I'm going until I arrive at BWI.

How much do taxis at BWI charge per mile? I can't seem to find a rate schedule online.