Is the key to using blogs (or journals for that matter) to chronicle your life knowing how personal to get, how much of yourself you reveal? My mother told me that she has just finished writing her autobiography. If it were extremely personal, I don't think I would want to read it. Yet I would want it to be somewhat personal, or else it might just be very boring. You want there to be a voice, an opinionated voice, not just a record of events.
And I don't think I feel this way just b/c its my mother. I try to imagine what it would be like to read an autobio from someone living 150 years ago in Texas. If they went on about who they had a crush on, etc...well, maybe that would be interesting. Its not only sex life that has gotten left out of so much personal history over the centuries; its emotional life. So maybe you do want to leave in some of the personal stuff.
Ultimately, blogs are like any art, maybe even like any conversation you have - its not whether its personal or not that makes it of value. Its your ability to convey your conscious experience of life without being trapped inside your own head. All communication, like our consciousness, is editing - there are a billion experiences every instant. Our minds weed out the irrelevant information about the physical world (sound & light not audible/visible to humans). Artists/bloggers/conversationalists extend that process to their own experience, to the social world.