What to include on a sitemap for a huge site?

[CFSSEO]

I have a very large site and I'm not sure what all to include on the sitemap page.

We have categories such as items1, items2 and in the items1 category are 100 vendors with their individual vendor pages.  Should I link all 100 vendor pages on the sitemap or just the main items1 category?

[Copstead]

What is the goal of the sitemap.  And I'm assuming you are talking about a html sitemap, not a XML sitemap.

If it is for users, guide them to the best category pages.

If it is for SEO, don't have one.  Focus on building organized XML Sitemaps.