I think the period beginning with the 1988 presidential campaign and running through the mid-90's is up there with the first 4 seasons as the strongest two runs of the show. And I think you can in fact argue that it was the all time best era. So much classic work was done during that time.

Watching the DVD sets of the early years, I was surprised at how rough and unpolished the show was. It was still good, but they made a lot of mistakes, blew lines, fell out of character, etc. I don't know if it was a lack of rehearsing, the reportedly widespread drug use or what. Probably a combination of things. Plus, by the 90's, they had the formula down.