[SFF]

I have each "bucket" that you mentioned (Work, Personal, Legal, Marketing, etc). set up as a folder. I consider these to be equivalent to "Areas of Focus"/20,000 ft level in classic GTD terminology.

I get around what you mentioned as an inability to assign tasks to folders by having a Single Action List in EACH folder (i.e., inside Legal would be a Single Action List called "Single Tasks - Legal"), then any individual action that is not a part of a project simply gets put into the appropriate Single Action List within the folder.