Check out Wycliffe Gordon and Jay Leonhart, "This Rhythm On My Mind". Lots of vocals, as you might expect from those two, but a quirky, fun album.
Trombone and bass are my "double" - of course, if I did a duet, I'd just be playing with myself ...
Christopher 401T / Gage Realist Soundclip / Fishman Pro-EQ Platinum Bass / fdeck HPF-Pre Series 2
NS Design CR4M EUB / TC Electronic RH450 & Markbass F1 / BFM Jack 112