Benidorm springs to mind with me.
The show started off really good, i used really like it.
But after about the 3rd series, it started to go downhill then. Basically because some of the good characters left (e.g. mick, janice, chantelle and goeff) and the new characters that came along werent nearly as good.
Now i think its got to the point where its been dragged on too long.