Ultimate Rewards Mall Flight Warning
I tried to book a trip BDA-RDU.
On Orbitz I found the routing I wanted (well, not that I wanted but that I was willing to accept), which was a multi-carrier hop.
So I tried to go to Ultimate Rewards, to get the extra bonus points. (I think you get 2x on CSP for travel plus 2x for UR Mall, which is better than 3X Amex for airfare.)
However I could not book the multi-carrier trip. Also, looking at other flight options, there was a routing on JetBlue that was $510 on Orbitz, and $548 on UR.
So be very careful before booking on the UR Mall - you might not get the best routings or fares.