TOD:
"Friends" DEFINITELY should be included, Dr scratchclaw! From the very first show I was hooked and felt comfortable with all the characters. Season after season, each cast member revealed depths and nuances that most folks simply took for granted. Comedy is HARD. Ensemble comedy is HARDER. And these guys made it look easy from show 1.
And there's a lot to be said for "Will and Grace", too, if you count only the first five seasons (and forgive Season 3 for the excessive bitchy-nasty antics of Jack and Karen). For Jack Randall, I'll say this: If the creator's real-life "Grace" was offensive, selfish and unbearable -- and if he, himself, was so pathetic that he could not shake this cancerous appendage from his life -- then Debra Messing played her to perfection. I never "got" why Grace was in his life when he was supposed to be smart and savvy. I think that we never got to the crux of who "Will" really was because the show's creator could not reveal that much about himself. Unfortunately for Messing, I cannot "see" her as anyone other than "Grace". If there is anything REMOTELY Lucille Ballish about Messing, it's this identity with a character...and Messing loses bigtime because I hated Grace with a fiery passion.
"Buffy, the Vampire Slayer" NEVER had a miscast moment, IMO. The cast clicked from the git-go and every guest/added character worked very, very well. (I'll admit to not warming up to "Dawn" for about half a season, but she grew on me and became a favorite).
"Frasier" remains, for me, one of the finest ensembles EVER.
The first three seasons of "Dynasty", before the cast changes covered by tragic accidents (Fallon's auto accident and coma....followed by her recovery and -- apparently -- total amnesia as to what she looked like and how she talked) and (Steven's being trapped in an explosion on an oil rig, after which the slender, sensitive blond Steven morphed into a hunky, rather rugged Steven). For me, the show never recovered from the loss of Pamela Sue Martin as Fallon, but I loved it all the same.
"Stargate: SG-1" -- perfect casting. Even when Michael Shanks took a year off and was replaced by Corin Nemic, Nemic fit in so beautifully that when Shanks returned, I mourned Nemic's departure. After Richard Dean Anderson left and was replaced by Ben Browder, I found myself adjusting quite nicely to a different "Stargate" because other key characters remained in place and played by the original cast members. The addition of Claudia Black, Browder's co-star on "Farscape", added a great deal to the mix, I thought and made some wearisome plotting tolerable.
"Golden Girls" was, is and will always be PERFECTION in casting.