Cool thread! Ones that have left a mark as a challenge:
Outside CONUS:
Salinas Intl in
PR
one in Argentina name escapes me
Green Hell!
Imola
Autodromo Monterrey
CONUS:
The Glen
Gingerman
COTA
Road America
Road Atlanta
Sebring (in various configurations)
Homestead (in various configurations)
Daytona
Lime Rock
NOLA
Moroso
PBIR