The wife and I just stopped by Wine Country Motorsports in Sonoma earlier this week to buy our DE helmets. Excellent service and selection, and well worth the seven hour round-trip from Reno. I have a long oval head, while my wife has a round head, so unfortunately we can't share helmets. I ended up with a Stilo while the wife went with an Arai (which is odd, since Arais usually fit me better than her, but that's why I simply can't stand to buy helmets via mail-order!).
Also, make sure you get a balaclava, too. They help keep your helmet fresher, plus in the worst case scenario they provide important fire protection. Just make sure you try on helmets while wearing the balaclava.