"Daydream Believer" might be one of The Monkees' best known and most requested hit songs. Period. Peter Tork swaps the guitar for the piano, at least in the video. Clip is from when MTV acquired the series in 1986, marking the show's 20th anniversary.
Canadian country singer Anne Murray covered "Daydream" some 15-odd years later and, I think, took it all the way to #1 on the country chart.