I'm just guessing but it looks like an 8", 10" and 14" tiered layer cakes.
Unless she likes her cakes wide and fat, I would add another tier and maybe do a sheet cake or two to be cut in the back.
Including the top tier, sizes 6, 8, 10, 12, 14, and 16 would give you 308. Minus the 16, 208 servings.
If she likes the look of the 3 tier, just make kitchen cakes to make up the additional servings needed.
I'm doing a wedding cake for a friend at a late evening wedding with no other food. They are expecting 250 guests and we decided to do 3 seperate cakes 1 3-tier and 2 2-tier cakes on either side. There will be 280 servings of cake not counting the top tier for the bride and groom. This arrangement will make more servings than needed, but there's no other food so we thought some people might eat two pieces. The wedding is in a tent with no kitchen or back room space available for sheet cakes. We made this decision after seeing a photo here on cakecentral.
here's the cake calculator if you want to play with numbers:
I like the idea of having more than one tiered cake rather than the "hidden" sheet cakes. I have never liked the idea of the sheet cake thing myself.
If she wants the 3 tier look, an 8, 12, 16 would give you 180 servings according to Wilton's serving chart (2in. layers), then you could make up the difference with a kitchen cake (double layer sheet cake).
Thanks for all of the help! How many WEDDING servings are in a sheet cake? I would need about 130 extra servings if I went with just one tiered cake that served about 120. Thanks!
Wedding servings per the wilton chart are 1"x2"x4".
This is the Wilton wedding serving guide. based on 2 inch layers (2 layers per tier)
A 9X13 2 layer sheet will give you 50 wedding size servings.