I have to make a cake in a few weeks for my nieces birthday. My SIL wants it to be round, 2 tier and feed 30-35 people. She wants 1.5"x2" servings. I can't find a chart that gives me these sizes (I can find 2"x2" and 1"x2").

Can anyone help me. I was thinking 6" and 9" or 10".

6 and 8=36 round.

I don't follow any other chart other than Wilton, sorry, didn't notice you wanted a different size.

1-1/2x2x4 are Wilton party size servings:

http://www.wilton.com/cakes/making-cakes/baking-party-cake-2-inch-pans.cfm

6/9/10 = 12/24/28 party servings

Indydebi's illustrated guide to cutting perfect cake slices:
(Sooo much easier than Wilton's method.)

http://www.cateritsimple.com/id10.html

HTH