Severance offer, what should I ask for?

I was offered 16 weeks of severance after 16 years as a customer-service rep, and I have a few days to sign. I have read a lot of threads here and could not find my exact situation. I do not want to leave money on the table. What did you ask for?

Read the release carefully. Mine included things I did not expect, like a non-compete.

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