I always heard you want to pair your shoes with your belt, but here's a chart coordinating shoes with pants.
Purple shoes? This a list for pimps and Prince?
Speaking of style changes, I get that sneakers can pull down your look but I think youth culture is never out of style and I think dressy sneakers are well-accepted, especially if you're more concerned with comfort throughout the day.
TS -- the main rule for shoes is they much always be clean and well-kept.
Americans have got it in their heads you can judge a man by his shoes (as with fingernails), so it's definitely an area to pay attention and maintain. You can almost say that the rest of you can look like a tattered, wrinkled calamity but all is forgiven if your shoes are on point.