Have you tried playing much with the options in Fractal Terrains? I've been continuously toying with them to find a decent result, trying to find what base settings and randomizer settings make the more convincing result. I got it to make something more sporadic once but forgot - like an idiot - to write down the parameters before trying a new set. Of course, I keep meaning to ask Joe Slayton about how exactly the random value comes into play. I don't know if it's like setting the average base temperature and then the randomizer is creating a range both negative and positive, or if it's only negative or positive.