I'm not really sure if this is the correct category for this thread but I hope you all will be understanding and willing to help me out anyway, as you all usually are! =]

So pretty soon I will be making and decorating a 3 tier baby shower cake. It's not going to be big, as the mom-to-be only needs about 30 or so servings. My dilemma is that going by Wilton charts, a 6-8-10" serves 60 (which I know she doesn't need, but depending on the sizes of the slices cut, it will be less) and at the bakery I work in a 2 tier, 6"-10" stacked serves 40.

Wilton says their 6" and 8" together serves 32.. so I guess I'm wondering.. should I go with a 6-8-10" and give her all those extra servings or go with a 4-6-8" stacked cake, which is really small but would serve at least 36-37 (I'm just assuming you'll only get 4-5 slices out of a 4" round pan, it's not a Wilton baking tin).

Thanks in advance! And any other input/advice would be greatly appreciated.

you don't say if the cake is sponge or fruit. But i would always allow extra serving for people that can not attend the event and there is nothing more embarrassing than not enough cake.. i find that the wilton portion guide is a little small for the fruit cake. traditionally in the uk friut cake portion is about 1inch square.

Most likely, the cake will be sponge. But since it's not a catered event, I don't think the cake will be portioned into squares, like a caterer would, but rather slices. And that's why I'm worried if I make it just big enough to leave room for only a few extra servings, the slices could be cut too big which would result in not enough.
 

Give a cutting guide and diagram so they know how to cut it to get the needed number of servings.