Hi - I am making a cake for a distant relative this weekend and it needs to serve 100. The slices need to be more than wedding cake slivers. I am thinking about doing rounds stacked. What do you suggest?
First, wedding cake servings are not "slivers" ... they are industry standard, nice, dessert size pieces of cake ... they are not intended to be a meal .... industry standard is 1x2x4". I know that many people hear "one inch" and they think "Paper thin" or they think "sliver", but it's not.
here's a pic of 1x2x4" pieces: http://www.cakecentral.com/modules.php?name=gallery&file=displayimage&pid=1156785 They are about the size of a folded over peanut butter sandwich (and I've never heard anyone describe a peanut butter sandwich as a "sliver" of a sandwich).
Here's how to cut a cake to achieve those servings: http://cateritsimple.com/_wsn/page10.html
Now that the educational part of our program is over ....
Here's the wilton wedding cake serving chart: http://www.cakecentral.com/modules.php?name=gallery&file=displayimage&pid=1156785
If your family prefers a piece of cake that is, for example, twice as large as a standard serving, then all you have to do is make cake for 200 per this chart. If they want a piece of cake that is 50% bigger than the standard serving, then you need to make cake to serve 150.
We can't really tell you how much cake to make based on "need cake for 100 but need bigger pieces" without knowing what you call "bigger".
If they need bigger pieces, just make a bigger cake.