In the 1990s, when the group was still on an extended hiatus, Sting invited Copeland and Summers to his wedding to Trudie Styler. Knowing that the three members of the band were there, the guests pressured them into playing live. Wearing tuxedos and not entirely sobre, they did.
More of a solo example for Sting: the Kennedy Center Honors paid tribute to him in 2014. The covers (by the likes of Lady Gaga, Bruce Springsteen, and Bruno Mars) were all great, but the kicker came when the cast of The Last Ship (the musical Sting had written the music and lyrics for, which was then on Broadway) came out to sing during "Message in a Bottle." Considering how personal the show was to him, Sting was so happy he started crying.
Andy Summers teaching John Mayer the proper way to play "Message In A Bottle" back-stage at one of their reunion shows. John Mayer, say what you will about him, is an educated classical musician. Andy's almost casually schooling him and Mayer's genuinely in awe.