I was asked to make a 2 tier cake for a little girls birthday, they want the cake to feed about 26 people, what sizes do you recommend for the tiers??

I would say 6/8" and they'll have some leftovers.

I am always more generous in my serving sizes. You are also talking about party size cakes servings and not wedding cake serving. If you ever need to know a basic serving, even thou they are not exact, use your Wilton chart for servings, that will help you alot when determing serving sizes. I thinking about 2) 8" inch rounds stacked. There are many different opinions on this subject. You have to find the chart that you think is fair and works for you. It doesn't cost you much more to give extra cake. Its the time and talent they are paying for.

I would say a 6 and 8 would be good, and still have some left over. I would also consider if there are little kids as well as adults