Fact: your groom and groomsmen will not keep their jackets on for the entire reception. This means, that your photographer and all your guests will be seeing (and photographing) his under goodies. No, not that kind.
What your man wears is important. And how he pairs his shirt, tie and suit is even more important. I'm all about the patterns, but their are rules when it comes to suit pairings. Think same pattern, different size (with exceptions to the rule, of course). For example, if you're wearing a thin striped shirt, pair it with a bigger bolder tie pattern.
Because I think this article so perfectly puts these combinations and is my go to for menswear advice, take a gander at: How to Pair a Shirt and Tie.
[Except I really disagree with the paisley comment. Listen to me men: paisley rocks. You are man enough to pull this off.]