Blowout has the most extensive outreach program. Message Boards, advertising on blogs, huge promotions, sponsorships, post 100 times a day on Twitter, etc. Also Chris is all about customer service
DA Cardworld, once my favorite and go to retailer has a blog they post on once a moon, no sponsorship that I am aware of, no message boards, they do have a facebook page, but overall DA doesn't do a whole lot. I have gotten great customer service from Da with the exception of 1 time.
Big T sportscards. Big seller on Ebay that actually has the stones to post actual auctions of cases rather than overpriced BIN crap that most have. No message boards, no sponsorship, no nothing. Fast shipping, in other words they get the stuff into UPS's hands fast but it still takes 7 months by wagon to get to Oregon
Atlanta Sports Cards: Josh gives quick service, and Atlanta has started message boards that are kind of catching on. Not much else than that. Shipping takes forever to the West Coast. Atlanta uses Twistter, sponsors FCB if I recall but no blog outreach
Pgh Wholesale: Who? Exactly, but decent prices.
Orange County Sports Cards: Good sale, No promotion and I happened upon their site by pure accident
So why the difference? Enjoy the traffic.