Hasn't anyone tried The Hardest Part yet? It took me a while to get the whole thing but I finally got it down. Great song to play.....tough one to learn though.
Other songs I like to play are Politik, A Message, Fix You, Amsterdam, Trouble, and Warning Sign.
I have their first two albums for sheet music so I can pretty much play anything. I just recently started playing the piano again after about 10 years of not playing because of Coldplay. They have such great songs!!