You really can't go wrong sitting anywhere in this theatre. I sat in the first row of the mezzanine and was in heaven. Both of your seating options would probably be fine...but keep in mind that R would be partial view (I think). You miss the top level of the set, but only like 30 seconds of actual stuff happens up there anyway. I have heard people say that closer is better, but the Booth is so small that anywhere is fine, really.
"Art, in itself, is an attempt to bring order out of chaos."-Stephen Sondheim