Yes, exactly! I only ever flocked out personal information/work stuff -- but if I'm dividing the work stuff into a different journal, then it's hard for me to see what I'd lock here. And I'm sure there's something, but since I don't know what it is yet, it's hard to make a policy for an imaginary future. :)

D'you know offhand if you have to grant people access in order to put them on filters? Because I do use filters sometimes -- mostly for things like birthdays (leaving the birthday person out) or for things like collaborative projects (leaving collaborators in). Which would mean I'd have to grant access to some people, and if I have to do that already, then maybe your third option is best.