Having empty chairs across from the bride and groom is a Scandinavian tradition I first saw at a wedding in Seattle last year, where the bride and groom chose to incorporate traditions from the groom's native Sweden. There, the signs aren't necessary, guest just know that they are invited to come and chat.
Take a picture of exactly how something is supposed to look (i.e. centerpieces, place settings, cake table, buffett, etc.) then place it on the container that has all the pieces inside it. That way whoever is setting it up has no questions and knows exactly what the end product/display should look like.
Here's to the guys who are usually clueless what to do. They want to get married and that's about it. Well, there's a bit more to getting hitched. This handy graphic will help you get things put in order so you can live happily ever after.