I am planning out my first wedding cake: a square one. They want to save the top tier and need the cake to serve 200. Is there a way to make this a 3 tier cake without it looking goofy and if so, what size tiers should I use. Has anyone done one that they can show me pics of so I can see what the sizes will look like together?

I just bought the Wilton square set. It is suppose to be for a 200 serving cake (minus the top tier). It is a 16, 12 and 8 inch set. The 16 serves 128, the 12 serves 72 for a total of 200. The 8 inch serves 32 but can be used as the keepsake.. This is on a 2 layer cake.

Have you looked in the Gallery? There's a bazillion photos of square cakes, and many of them have descriptions that tell you what sizes were used.

Here ya go: http://cakecentral.com/modules.php?name=gallery&aid=83