I also remember him as a music buff. He loaned his name and image and did some creative work on a number of light jazz/mood music albums (as in "Jackie Gleason Presents...") back when that type of music was more popular. Surprisingly enough, they weren't just money grabs using his name. He was actually a connoisseur and took an active role in the production of those albums.
Here is an interesting one. At Graceland, every year they have a virtual concert, with live performers, with the exception of Elvis, whose image and voice are I think a hologram or something similar. Much of the footage of Elvis is from the 1973 Aloha Concert. The man playing lead guitar is James Burton. You can see his age difference of 25 years! Awesome guitar player and an awesome song, Johnny B. Goode!