It’s hard to know what to love best about Coldplay — the music, of course, every rock ballad a smashing crowd favorite, but there’s also the high-energy stage presence of the band and its evangelical, marching-band leader. Then there’s the colorful retro grunge clothing reminiscent of the ’80s, the painted guitars and piano; and the pulsing laser light show complete with drop-down balloons that alternately chang...