I've gotta go with the Baja Marimba Band version here. To me the song should be an instrumental as that's the way I first heard it on the radio. The version that I heard most was the one from Sounds Orchestral. I have that version on the CD called Golden Age of American Popular Music: Hits with Strings and Things.
Honestly, I don't really like any of these. I'd probably pick the Sandpipers version only because of the swinging arrangement behind it...but don't really care to have their perennially sleep-inducing vocals on this track either--if they omitted the vocals and added Julius to make this a Baja recording (and let's face it, the studio bands behind both were most likely very similar), it would have been perfect.