Go with one of the name brands. H. Upmann, Hoyo de Monterrey (Excaliburs are my personal faves), Romeo y Julieta.
Do you know if he likes a strong or mild cigar? If so, ask the cigar shop which of the name brands to pick out. Most of them make both a strong and mild version, and you can't always tell from the wrapper (dark doesn't always = strong). You could also hedge your bets by sending him a variety pack of different cigars that you pick out as singles. If you're worried about humidity, most cigar stores will sell or even give you a small shipping wafer that absorbs water and keeps more than enough humidity for shipping in the continental US.
