I went through the Extended Look and listed every location that is actually named on screen

Rules I set for myself: it counts if a sign, a marker, or the narration names it. No guessing from architecture.

1. Vice City, and inside it Ocean Beach, Little Cuba, the Stockyard, Crosstown, the VC Port.
2. Leonida Keys.
3. Grassrivers.
4. Port Gellhorn.
5. Ambrosia, with the Allied Crystal refinery.
6. Mount Kalaga National Park.

Road signage also gives Vice-Dale County and Kelly County, which are counties and not regions. Everything else people are posting is inference. Good inference in some cases, but inference.