The walnut would be great for you! They're really actually only different she compared side-by-side. Blackwood is quite thumps in the bass (still detailed and tight) and has a somewhat more energetic and aggressive sig. Treble has bite but is still smooth. Walnut is similar but slightly less aggressive, still with tremendous bass slam, still a smooth sig, maybe a little more balanced than black woods. Cherry is very linear, least "thumpy" bass. Someone at the Chicago meet told me they thought it was slightly mid-forward, but I heard it as perhaps the most linear/neutral of the bunch. Biggest soundstage too.
In terms of looks, you can check the Chicago meet impressions thread, or wait till Zach posts pics, but I have to say the Walnut and especially cherry were even more gorgeous than the pics on the website. By a lot. Black wood looks nice, but if you want looks and the more blackwood type sound, walnut is a good bet. Cheaper too!
YMMV, but hope that helps.