Recently read that before Kelsey was considered for the role of Frasier Crane, the producers of Cheers had approached John Lithgow! Lithgow who is 10 years older than Grammer (and looks it) wisely turned the role down.
Can you imagine a middle aged Crane in Cheers and a pensioner in Frasier this would have knackered Mahoney playing Marty as they look the same age easily! DHP couldn't have passed as the slightly younger brother and Neuwirth would have been a trophy wife being 13 years Lithgow's junior!