Severance offer, what should I ask for? - any advice?

My manager said the package is final, but the letter gives me time to review. I worked as a retail manager before this. It includes health coverage for a couple of months. Did anyone negotiate and succeed?

An hour with an employment lawyer cost me a small fee and made me feel much safer about signing.

I asked for two more weeks and a neutral reference. They agreed to the reference and added a week.