What I would love to see on Facebook is a way for me to make all non-starred posts older than X private. That way I can post lots of stuff and have the recent timeline filled with all sorts of crap which gives an impression of me, now, but it also allows me to hide all the old and only bring out the highlights, the things I actively want to be visible.
The problem is that the things I want to be visible changes with time, so I can't just not post it in the first place, because what seems perfectly fine today may be really bad a few years from now, and I can't know that ahead of time. And there really is no way to delete everything as far as I know.
I would like something similar as well. Perhaps some way for friends to only view my history back to the date where I added them as a friend, that way my oldest and closest friends have access to all of our history together and my newest, less familiar friends only have access to the me they've only ever known.
The problem is that the things I want to be visible changes with time, so I can't just not post it in the first place, because what seems perfectly fine today may be really bad a few years from now, and I can't know that ahead of time. And there really is no way to delete everything as far as I know.