what exactly are you looking for? im guessing you just want aftermarket wheels to say that you have them since youre concerned about ride quality. if you want the "look", 18s are the way to go. wheels dont effect ride quality as much as tires do. ebay has a nice set of wheels going for $650 shipped and theyre also being sold by a company, which is always a big plus: http://cgi.ebay.com/ebaymotors/ws/eBayISAP...item=2468160645
you can then score some tires from the tire rack depending on your taste. end price will be over $1k because of the simple fact that the wheels are 18s.
now if youre looking for something that will get ya to the grocery store quicker, 17s would be my suggestion. the average 17 is lighter than the average 18 (duh!) and everybody knows that you want to reduce rotating mass; rubber weighs less than steel, so we would want more tire than wheel. personally, im looking at a set of 17x7&9 asa ar1's:
wrapped in 245&285/40 kumho ecsta supra 712's
as for "capitol" tires, i have also never heard of them.