I try having a family member drive me first, and gamble on having someone available for the ride home otherwise it's a taxi. I don't currently have a car but when I did if it is under a seven day trip I drove and parked at the airport (MSP, expensive) but if it is over seven days it is cheaper to take a taxi both ways.

I also try and use public transportation when possible at my destination. Fairly easy to do on the east coast but challenging at other places.

Cheers,
Pogopossum