This is for 3" deep pans
http://www.cakecentral.com/article15-Cake-Baking-Cutting--Serving-Guide---3-in-Deep-Pans.html
This is for 2" deep pans
http://www.cakecentral.com/article14-Cake-Baking-Cutting--Serving-Guide---2-in-Deep-Pans.html
Good Luck..
Don't forget that the couple usually wants to take the top tier home for their anniversary.
As for which sizes look better together it depends on the cake design. If you need lots of space for decorations on the side you may want larger spacing, otherwise the 2" spacing between pan sizes may be enough.
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