It's saturated in places you would expect, on the coasts. Best salaries are in the midwest > the south, outside of the cities.
Depends on the gigs but yeah nocturnist jobs in the above areas you can find 14 nights for ~400k but be wary of the other factors as well, including # of admits, if you have APP help or not, length of shifts, how many hospitals you cover, code responsibilities etc.
APPs are largely not taking over hospital medicine, too much breadth and they miss alot of stuff. They're around but they can't replace you, if you work with any take a gander at their notes and orders and you'll see why.