Bryan Kimsey has set up my two Martins - I follow his advice when I do my own
E = .022", A = .020", D = .018", G = .018", B = .018", E = .016"
The quick check is a hair of clearance at one when capoed at two. It will be very slightly affected by the rest of the setup, but usually it is the first thing I set (providing relief and action are pretty close).
Fwiw - I also follow Bryan's advice on relief - generally 6 to 8 thou on my fingerpickers - he has a three page analysis of relief vs action (and the effects on buzzing at different places)
http://www.bryankimsey.com/setup/index.htm