Keith, those are great examples! I definitely think Grady filling in for Fred turned out amazing and who would've thought that he and Lamont would have such great chemistry of their own? I will also add an example with Kirstie Alley replacing Shelley Long on Cheers. Nobody thought the show would survive without Shelley Long and the Sam\Diane thing but Kirstie came in and the show actually thrived better than ever in ratings and in comedy. I personally prefer the Alley era myself.