Law School Discussion

I've been out of UGrad for a few years now, finished grad school two years back.  I've been working as an intelligence analyst for over two years now.  I am planning on getting one letter from my thesis advisor from my MA program, for the other I am debating between another professor that I did research for in grad school or my boss.  I am hesitant to get a second letter from the professor because part of me is still considering ditching law school and doing a PhD (maybe applying next year).  I figure if I ask him for a law school letter, it may tarnish  my image in his eyes if I apply to his program next year.

Plus, my boss is obviously very familiar with my work over the last two years, which I think parallels with the type of work lawyers do with the written analyses of complex situations, etc.