I would like to have access to a much longer list of folders to which I have recently added bookmarks when choosing where to add the current bookmark. The list is currently limited to something like 5-7, but often when I am bookmarking a lot of new URLs, I want quick access to a folder where I bookmarked a page ten or twenty bookmark additions ago. This seems like it would be a relatively simple and safe enhancement that would save users a lot of time.
Also, I and a lot of other users, from what I can tell having researched this online, would like there to be an effective and easy way to permanently delete a URL from the list of suggested URLs that are offered when typing in a new URL in the address/search field. I use the recommended technique to delete them, but it's never permanent. The next time I launch Firefox, all the old suggestions are restored and I have to delete them again. Many people have encountered this frustration and asked for this feature. I'm adding my voice to the chorus.