Health insurance and 401k are top notch.
Location, like the weather and being near the mountains.
Collaboration between programs. Each program is very possesive off their own emplyees. Very difficult to loan out an employee (who has free time) to another program.
On site visits/interviews should be standard prior to issuing an offer. On site visit was made part of my house hunting trip, which was part of my relocation offer. Basically if the on site visit went poor, and i tuned the offer down. Then i had to pay out for the visit...