I am making a wedding cake to serve 150. I really didn't want to go higher than 4 tiers, including the top tier that won't be served. I am not sure what size tiers to use to get that many servings, but then not having the top tier be so much smaller than the others. If I did a 16/14/12, that would give me enough servings but then if the keepsake tier is only a 6 inch, would that look funny? Any suggestions on sizes to use? Thanks!