Should I negotiate my severance? - any advice?

I was offered 3 weeks of severance after 3 years as a retail manager, and I have a few days to sign. I do not usually post, so bear with me. It includes health coverage for a couple of months. What did you ask for?

Thanks for writing this out. I went through something close to it 2 months ago, and it got easier once I kept a simple log of every call and form.