Last name on Direct Mail?

[David Hodge]

I'm sending out a few hundred yellow letters to multiple neighborhoods about 15 minutes from where I live.  This is our first direct mail campaign and we're hoping to get one rental out of it.  My question is, should I include my last name in the return address?  We have a P.O. box so my personal address won't be on it, but my fear is that someone could look up where I live if I include my last name.  Am I being overly cautious, or is this a legitimate concern?  What do most people include in their letters/envelopes?