So I am making a cake for a good friends in-laws 40th anniversary. I am doing this as a favor. So I showed them my white spiked pillars and they thought she would like pillars. I was kind of glad. Lately I have done stacked cakes. So they will be 8 and 12 inch. I will put the bottom one on a 14 in. plate and the top one on a 10in. Wilton Plate. Does that sound right?
I think you may want a bigger plate on the bottom than 14". The 12 cake on the 14 plate will only give you one inch of room at the most for borders and such.
As for the 8" cake, as long as you're ok with the plate showing then you'll be fine with the 10". Sometimes I like for my plate not to show...then I'd go with an 8" plate.
I guess it really depends on the look you are going for. The configuration you have in the OP will work just fine.