I have not come across serving guide for 3inch deep pans. Not sure if they are the same as a 2inch deep pan, which I have already looked??? Also, if you stack 2 cakes the same size to equal 1 tier...how would you determine how many it feeds??? Hope this makes sense...Any information would be helpful

im pretty sure wilton have that on their site, sorry i dont have the link saved on this computer.
xx

as far as stacking 2 cakes for one tier, i think the general consensus is that you get the same number of servings, just twice the cake height,.... since to make a real impact on the # of servings (say, to double them) you'd have to cut each slice so thinly that it would be counterproductive...

Yes, the thinner the cake, forget about how tall it is, the smaller it looks, and hence people will think they are getting jipped. So if you want to make them taller, go ahead, but I wouldn't try to get more servings from it.

wilton's 3 inch deep pan serving guide has the same numbers as the 2 inch deep pan...however, it states this:

"Serving amounts are based on party-sized portions of approximately 1.5 x 2 in. Cakes from 3 to 6 in. high, baked in the same size pan, would yield the same number of servings because they follow the same pattern of cutting. Cakes shorter than 3 in. would yield half the number of servings indicated for that pan. Number of servings are intended as a guide only."

it says the same thing in the 'wedding serving guide' also

i keep this link VERY handy!! i am ALWAYS referring to it http://www.wilton.com/cakes/making-cakes/
on the right, the 4 serving charts are under "baking time and batter amounts"