Suggested feature for Safari- Cookie Whitelisting

I'm not sure if this is the right place to do it, but I'd like to suggest a feature for Safari: cookie whitelisting.

I can't find a way to delete cookies while retaining the useful ones.

There are several websites I visit that offer useful cookies- generally the types that remember my login. I'd like to be able to delete all cookies except those of my choosing (which usually provide some beneficial service). I'm not sure if this means also implementing a layer of transparency over what the cookies are actually doing, but that would be great, too.