I use tabs like bookmarks - sites that I might need now or a bit later. I GC them from time to time. Actual bookmarks are used for things like sending a link to myself at home using firefox sync or bookmarking sites I need to visit again and again, like docs sites, the internal bugtracker, etc. I don't open those from the bookmarks menu though, I just type in the awesome bar and firefox always shows bookmarks first, i.e. I use bookmarks as a manual way to bubble up search results in the awesome bar.
I use tabs like this too and I'm not really happy about that, I just haven't found a better alternative yet.
What usually happens is I'll be browsing and find an article/code library/inspiring web design/useful tool that I know I can make use of later in some way, but if I just bookmark it then I'll probably forget it's in there.
I have very organised bookmarks but these only work for sites I visit often and I do use tools like Evernote and Gimmebar but it still doesn't feel right.
