Cheers was a wonderful show; I still watch the reruns on tv all the time, and it still has the ability to make me laugh, even when I've seen the episode over and over; even when I know what the episode is from the very first line. I still laugh, because it's just a funny show.
It had a great mix of characters, and even when circumstances didn't allow those characters to continue (ie: Coach), they managed to replace the one with another who, while not the same, was a good fit with the rest of the group. There were characters to love and characters to hate; characters to sympathize with and characters to laugh at. Cheers had it all.