What type of suit should I get for a wedding?

If you are the best man, they should tell you what they want you to wear. You don't mention much about the other wedding-is it day or evening? It may not require a suit, just a nice dress shirt and tie or slacks and a sports jacket. Try some place like mens wearhouse, they will have a good selection and should be able to ist you in picking out something appropriate that looks good on you. I think they also do tailoring which is important because very rarely does something fit perfectly right off the rack. I also think they have the whole shebang including shoes, so its a good one stop shopping trip.