I also have been out of school for several years and had 2 of my bosses write recommendation letters. While I work in law and they had concrete, applicable things to say, I also included a copy of my PS for them to read. My PS details a part of my life not readily apparent and includes info neither of my writers knew about me. Both commented on how they appreciated reading the PS and how it helped them place a context around the letters... I gave them the PS while it was still in draft form.
Good luck to you!