I would like KHEF/Manassas Va. Pretty prominent municipal airport just south of KIAD. I’d be happy with a simple build as it’s so close to KIAD it can’t be a hog of an airport. ETA: cripes they have it as freeware-I need go get this PC built STAT.
Lakehurst NJ would also be a cool place for a makeover with all the past and present oddities there. Everything from Hangar 1 to the electromagnetic catapult launch to the rocket rails. Remnants of runways and countless testing areas everywhere, even an F4 tribute.