I really like both the Decemberists and Ryan Adams. But I've also already seen the Decemberists in '06. I really enjoyed their set. However, the Crane Wife doesn't strike me as an album with a lot of good live songs. Although The Island, Come and See...(that 12 minute song) would be pretty epic!
If I had to choose I'd definitely go with Ryan Adams. If he brings the Cardinals along I'd hope to hear mainly material from Cold Roses, 21, and Jacksonville City Nights. Easy Tiger not so much.
But hey if either are added i'd be very pleased indeed.