It's a math problem never seen on one of those tests that asks about the trains leaving in opposite directions, etc., etc. How many days will my parking at the airport cost vs. how much will the cab fare be round trip? For a while, a trip of more than 10 days made it more economical to take a cab than to park but then cab fares went up and now, provided we have a coupon, that extends to about 14-16 days being cheaper than a cab.
Alas, we have heard that several of the out lots have been purchased by our airport (CLE) so we are guessing that prices will go up even more to park since there is almost a monopoly. So we are back to more mathematical calculations to try to save some travel dollars. There are a few creative ideas.
Some hotels near an airport will offer free parking if you stay with them the night before you fly. Ten, fourteen, even thirty days may be in the stay and park package. We've done that twice in the past--once when we drove to Detroit to fly somewhere because the airfare was cheaper
Of course all of this leads to more calculations. All airport parking lots are not created equal. I was surprised to hear that Charlotte's only charges $5/day. Most in our area are around $7 to $8 a day. Then there are some I've heard are as much as $15/day.
A cab looks pretty economical in many instances. Ask around to find the most reliable. You don't want them showing up late or not at all. Of course if you have a friend who doesn't mind some of the crazy flight times, you might just get a ride back and forth for the price of a nice souvenir.