I agree with kags seemingly 99% of sit-coms run and run. Now I don't know whether it's the fact that they become tiresome following the same routine, or whether it's that its viewers mature, or a combination of both... but what I do know is that stopping a sit-com at the right time is much more intelligent and highly commendable in my book, and makes it even better. I know The Office may not be a sit-com, but it is a prime example. It's about the best programme I've ever watched on television and, although I was distraught, I had to admit that stopping it after a second series (and Christmas Specials) was just about the best thing that ever happened. Imagine if it had gone on to a third season and somehow not been as good? It would have unnecessarily marred the whole thing. Not unlike Only Fools and Horses - obviously it still has its fans, but the old ones are still classics, whereas the newer ones started to become tiresome and unfulfilling.