Actually, I think big coaster in the Homestead would look awesome, it's just a matter of how you perceive it. I don't think every major ride needs it's own themed area - just look at how ThuNderaTion fits in so well.
^^^Well, I'm not really saying that it's just a jumble of rides... I too think it was pulled off well, just not like I think it could be. To me it feels more like a quaint park surrounded by rides, which at this point pretty much fits the theme of the area. I just think a big ride plopped down next to it would throw it off. Of course, who am I to say what will or won't throw things off? It's easy to forget that the park has planned everything out, and I'm sure they won't go wrecking themes and throwing off atmospheres by throwing stuff around where it doesn't feel right. If they decide to put a huge coater by EH, they'll make it work. They always have.
I think by now though we've all pretty much shown that the evidence points directly at a major G-Fighter being the big 2009 project - so the question now is - what will it be like? Will they go with the mine theme again, or are they going to surprise us with some sort of out-of-the-box, wild, could-only-happen-at-SDC amazing theme?