I have seen Wilton's Guide for servings & I have seen Earlene's which one do most people go with?
I have a friend who wants me to make her cake & she is having approx. 115 people so I'm not sure if I should suggest a 10 inch & a 14 inch for 116 pieces or if I should suggest that AND a 6 inch as well "just to make sure". What do you suggest?

who's cutting the cake?

if its a professional, they tend to go by the wilton chart.

here's pics of 1x2x4" pieces of cake. A lot of folks hear "one inch" and they think "paper thin" .... as you can see, it's not. http://cakecentral.com/gallery/1156785

In my signature link is a pictorial how-to on how to cut a cake to achieve these size pieces and the number of wilton servings.

If its family cutting the cake, it's hit or miss.

Thanks Debi, I will ask her just that, who will be cutting the cake? Those portions are very generous and oh so tasty looking