Severance offer, what should I ask for? (Fresno)

I was offered 16 weeks of severance after 16 years as a hotel front-desk agent, and I have a few days to sign. I am in Fresno, in case local advice matters. There is a non-disparagement clause. Should I see a lawyer?

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