When I talked to the asst dean of admin at the local school , she didn't place too much stock in LOR's - Her words were something like - Anyone should be able to find three people to say something nice about them. But I think every school is different. For me, being out so long, I went with a former employer and a friend who's an attorney. I only needed two LOR's, my third would have been a graduate prof who I had worked with in a previous job a long time ago. IMO you want someone who can speak about your ability to succeed in LS, your upstanding moral character, your work ethic, your leadership ability, etc. Generally profs have a handle on your work ethic and your ability to succeed, but employers would be a good alternative.