There are lots of defunct military bases. Fort Ord, in Monterey, CA, was closed in 1994, and it's still underutilized. Great weather, near the beach, near a reasonably sized city, and still a tough sell.
Closed as an air force base in 1966 and turned over to the local government, https://en.wikipedia.org/wiki/Grant_County_International_Air...
Closed as an active SAC bomber air force base in 1969, https://en.wikipedia.org/wiki/Clinton-Sherman_Industrial_Air...