I grabbed this from the recipe board. I just baked a spice cake tonight, torted it with Polener's (sp?) Sugar free blackberry jam... I tasted it with the extra from leveling... Man... is it good. Oh, and it was just a tiny leftover batter cake, 1 6" layer.

But this recipe below... I'm assuming it will cover the entire layer?

Serves/Yields: 1 cup. (8 servings)
Prep. Time:
Cook Time:
Category: Frostings
Difficulty: easy
  
This frosting is good for many types of cakes including carrot cakes, apple cakes, and spice cakes. Add flavorings to compliment the cake you are frosting. Try 1 1/2 teaspoons of grated lemon or orange rind, 1 teaspoon any extract, 1 teaspoon of liqueur, or a mashed banana.

1/2 (8 ounce) package cream cheese
2 tablespoons cream
1 cup confectioners' sugar

1 Blend together the cream cheese and cream until light and fluffy.

2 Sift the sugar, and add to the cream cheese blend.


***

Then, anyone got any ideas on how to decorate? (This is just a practice cake for my family.)

I imagine a normal 8 or 9 inch pan, or a 9x13.... I cant see it covering more then that... I could be wrong....

http://www.wilton.com/wedding/cakeinfo/cakedata.cfm -per wilton's site it takes 3 cups of icing to ice a 2 layer 8" round, and I have found that to be pretty accurate.
But you might want to mix up a single batch and actually see how much the yield will be.