the groom, 3:

third, a dark suit (my personal favorite).
this one is as sharp as it gets while avoiding a tux. the suit should be dark, and if not wool, the fabric should not wrinkle very easily. here, the clean lines and lack of details make the statement. a crisp, white, semi-spread collar shirt with french cuffs is the standard - don't stray from that.  if you want a pocket square, it should be just as crisp, and just as white as the shirt - consider running an iron over it after it's been folded. most importantly, the suit should be trim and tailored. slimmed out sleeves, high armholes, narrow and tapered legs, etc - you should not be able to successfully throw a football while wearing a correctly fitting suit.

a dark suit can be killer in the summer; the heat will not be your friend. a light-weight wool will bode best, but know that if you plan to be outside, a dark suit will warm up quick. on the plus side, a nice, quality dark suit looks sharp and formal, even when compared to a well-tailored tuxedo.