Considering my playing style, what type of acoustic guitar "top" should I look for? Spruce, Cedar...?

I really have to recommend Carvin's Acoustic Cobalt series. Their lowest model is about $490, fits right in your price range. Carvin operates their own factories to make their guitars, aka they sell direct, as opposed to retailing, so their guitars cost much less than they're worth. I have an upper range Cobalt and it's the best acoustic guitar I've ever played. It obviously won't compete with a high end Martin, but these guitars really are high up there. Definitely much better than any $500 guitar you'll find at guitar center. I seriously recommend you check them out.