Are there any travel/airline websites out there that allow searches in specific classes? For example, I want to fly to Europe and use miles to upgrade...I'm trying to find the lowest upgradable fare (B I think)...expedia, orbitz, nwa.com, etc. only either give unrestricted and restricted fares, with little choice in the fare class. I did find one site that shows the class, but you can't search for the class...any suggestions?