Sometimes I think Frank was at his vocal peak in 1961 - jazzy, rhythmic, elegant, carefree, and in perfect voice -- but he does so many great things later, and earlier, that I guess I should only say that he was surely in the zone when he recorded Ring-a-Ding-Ding!
Here's Fred and Ginger's take from Swing Time, my favorite Astaire-Rogers musical. You'll notice Frank didn't use most of the lyrics that were sung in the film, which is a pity:
In his must-have book linked above Mark Steyn writes:
This one's a keeper -- more and more recordings every year. If you want a fun one, try Marilyn Monroe's, of all people. (p 25)So I did, and it is --
Wow! I had no idea!