I would like to spend some time with Jazz as well, mainly because there is lots of material covering jazz improvisation. I hope to apply some of that theory to the harp.
One song I have messed around with is Moondance (Van Morrison). I will let you know when I have it figured out.
The piano and flute solos might be difficult, but I think the sax might be do-able on the (diatonic) harp.
Charlie McCoy has a nice version of "One O'clock Jump" by Count Basie that I like to play along with.
Fun song... just kind of need a nice big band to go along with it.. ( love swing music)
I couldn't find it on u tube but it's a nice version.
Saints go Marching in ...has a long jazz history to it as well...kind of like a jazz spiritual mix even
St Louis Blues was intended as a blues jazz transition from what I read and it has a nice feel to it.
Love the song.... play it often...
(I'm not an over draw over bend guy...just the reg bends and stuff like that)