When Bel Air travelers consider flying out of Philadelphia International Airport, as my family did recently, we often wonder whether to make a reservation to leave our car at an off-site parking lot or to gamble we’ll find a space in the economy lot at the airport. This was our first trip where we realized how tricky that gamble can be. My husband dropped me and the kids off at the check in and went to leave his car at the economy lot only to find it was marked as “full.” With only an hour and a half to go until take-off and no reservations at any off-site lots, his only option would have been to park in the airport’s hourly parking facility at a hefty price tag of $17 a day if he could find a spot on the airport garage’s upper levels or $38 a day if he failed and had to park in short term parking. Luckily, he drove on past that full sign in the economy lot and managed to find a pretty good space someone had just vacated. But from now on, we’ll be making a reservation at one of the off-site lots.