King's Hot Springs Hotel
Come in from the back and shoot up the walkway, then clean up the stragglers with companion fire.
Taking this outpost unlocks the 1987 Pygmalion Bruelag.
The outpost also contains an interesting bit of Faith's backstory.
The safe is locked in Room 301. Don't bother hunting around for the key- it's in the room as well
Instead, go east from Room 301 and out the open window.
Turn south and jump over to 301's balcony.
Inside you'll find the key on the bloodied bed, and the outpost safe.