Based out of PHL. Live in the triangle between I-76/I-476/I-276 (for anyone familiar with local geography), so a trip to PHL is 30 - 45 minute drive + 15 minutes park/TSA + boarding at T-30. That means I have about a 90 minute sunk cost in flying per departure and about an hour per arrival.

Drives: I drive to north NJ (2 - 3 hours) semi-regularly. I've also driven to Pennsyltucky (2 - 4 hours) regularly. I've driven Montreal to Ottawa (2+ hours?) and back as part of a multi-city trip nested in a PHL-YUL roundtrip by air.

Train: NYC (3 - 4 hours by car) is Amtrak & MTA when possible. Downtown Philly is SEPTA when I have meetings there. I once did Toronto to Ottawa (4 hours by car) by VIA to close an open jaw PHL-YYZ/YOW-PHL.

Air: I have done PHL-BDL, PHL-BOS, and PHL-RIC same day trips by air. That would be 4 - 6 hours for any of those driving. Flown to MHT, PIT, and ERI around multi-day trips. Also about 6-ish hours driving.

The key is whether or not the whole day is blown by driving. If so, a flight makes better sense so I can get a half day of work out of a travel day (either office time or client meetings).