Severance offer, what should I ask for? - what worked for you?

I was offered 12 weeks of severance after 12 years as a project coordinator, and I have a few days to sign. I would rather hear the honest version than the polite one. There is a non-disparagement clause. What did you ask for?

Ask for the offer in writing and do not sign on the spot. A day or two to think is normal.