I have totally been wanting to do the dash like that STi had. BTW, we call it suede, but if you order fabric, you actually want Alcantara. Suede fades with the heat in a car. Unfortunately, Alcantara is harder to come by as it's not available in fabric stores (that I'm aware of). The stitching is something I don't think I could do well enough. I really like the look of the dash though. Very Lamborghini-esque.
+1 for doing STi seats. Even 08+ WRX seats are a nice addition, but have blue instead of red. 09+ WRX's have red stitching, which might work out for you. I wouldn't mind a set of seats out of an EVO X. I have to be honest, I really prefer the EVO seats to my STi's.