I'd recommend Carapils for any brew that would otherwise be all extract. My peach cream ale was all extract and it has hardly any mouth feel to it.
I used 8oz. of Carapils in my hazelnut stout. Best beer I've ever tasted. I'm planning to use 4oz to 8oz in every beer I make now as long as I'm in doing extract brewing. But I should also say that I like my beers to be on the maltier side.
Planning: Agave Witbock, Raisin Beer
Primary: GF Hazelnut Stout
Tertiary: Cranberry-Pom pLambic (est. bottle date: 03/01/08)
Drinking: Cab.Sav/Merlot Wine, Grand Cru, Hazelnut Stout #3, Ordinary Bitter