I agree with Mark that 30fps would likely give a noticable increase in smootheness to the eye, and have minimal impact in the amount of film consumed.
Adding to that, it then fits inside one of the standard broadcast HD containers (60i) with minimal fuss, and eliminates 2:3 judder to boot!.
I've always wondered about film stock and processing costs. I mean for a movie with a double-digit-millions budget, is 25% more film really that big of an impact? I assume the telecine, storage, and FX costs would go up too, but still how much of the overall budget goes to such things?