A couple US-based airfields:
Falwell in Virginia:
W24 Falwell ‘ski slope’ Airport for Microsoft Flight Simulator | MSFS
I’ve landed at this place a couple times in real life. Fun place to go to. You only land one direction, take off the other. You can figure out which is which!
2NCO Mountain Air in NC. This is the highest airfield in the US east of the Mississippi:
2NC0 - Mountain Air Airport (Burnsville, North Carolina) for Microsoft Flight Simulator | MSFS
Safety, Originality on an Even Scale at Unique North Carolina Community - FLYING Magazine
There’s also a higher quality payware option available on the Marketplace that I own.
Ingalls Field Virginia: The highest public use airfield east of the Mississippi
KHSP - Ingalls Field Airport (Hot Springs, Virginia) for Microsoft Flight Simulator | MSFS