BifRayRock. Gray Line is now a world wide operation. (See Wikipedia). I am not sure when they dropped the Tanner name (which I believe was restricted to Southern California) but I can remember riding their buses into the early 1960s as they operated services to all the local area horse racing venues, a sport my mother viewed as an investment opportunity, and to which she contributed copious amounts of coin with little return!
Cheers,
Jack