I just saw them at the Verizon Center for their "Mylo Xyloto" tour, and I must say it was f-ing awesome. If you have the chance you should totally go see them live. My wife and I saw them back when they went on tour for Viva la Vida, and that was great too, but they definitely 1 up'd themselves this time.
We became fans a few years ago. We were in LA, and taking the backstage tour at NBC. We were outside of "The Tonight Show" studio, and there were some guys unpacking and prepping some instruments. The guide says, "this is the band." One of the members looks up and says , "we are the band!" I go, "hello band!" We saw The Tonight Show taping later in the day, and the band turned out to be Coldplay, and the member turned out to be Chris Martin. Fun story . . . and we enjoyed the music as well.
Here is a clip of what the show was like. They gave everyone a light up wrist band (xyloband) that they synced up with the songs. It was a pretty sweet show.