Hello, my name is Matt Baker. Charlie and Betty were my grandparents, and Tom is my uncle. Sadly he is gone now, however I am very aware of the story you told about the visit to my grandparents house.
Also, you were looking for the hotel they stayed at for their honeymoon. Turns out I live in Phoenix today and spoke to my mother before she died about this. She says it was the Arizona Biltmore most likely.
It is a very old and wonderful hotel. The resort has been an Arizona landmark since its opening on February 23rd, 1929.
Good luck figuring out who the piano player was. The incident you are referring to was a pretty cool moment in their life. Imagine being in a piano bar and hearing your song come on while on your honey moon.
And you are correct in that Tom got a scholarship to USC.
Best wishes, and feel free to reach out if you have further questions. Although, my knowledge is limited, I have access to the rest of my surviving family.