Ok, I'll say right off the bat that I'm a young guy, let's say early 20's, but I know a few things about suits. First off, stripes of any kind on a suit wouldn't be advised for anyone going in for an interview at a medical school. Stripes have a tendency of showing status, that's why you see a lot of business men wearing it. As students, we don't have much. Navy blue and grey are good choices, but if you want to pull off a look that shows you know a thing or two about suits grey would be better, darker grey for the younger person. As for black, I've seen young people pull it off very well. I think black looks best for a younger person and grey looks best for an older person. Try to avoid any colors other than the traditional solid colors of black, grey, and navy blue... but some might advise not to wear black. American cut would probably be best, since we're in America, and cuff-links are a big no (they tend to say you have high status, but again, we're students). Worsted wool is best for year round, and try to avoid the seersuckers for your interview, too informal. And definitely avoid croc, gator, and ostrich leathers (if you can afford them).