American brown is such a broad category, so its hard to make a reccomendation. Are you thinking you want it more malt forward or more hop forward? I have one fermenting now with 9 lbs 2 row, .75 lb aromatic, .75 lb crystal 60, .5 lb chocolate and .25 pound roasted barley. Hopped with fuggles, cascade, and wilamette.
Brew a few small batches and see what you like best. Good luck!