Just my 50 cents here...

There is an older Kontakt library that is little known, but has a very decent sound and contains all the bread and butter sounds you need. Vir2.com has the vi.one.

It is an older library, but still, a hefty 21 gb of samples. Pianos, basses are very good, the drums are really good. In comparison to the Kontakt factory library or JABB3 from Garritan, it is way better.

If you like trumpets and saxophones, vi.one has got some nice samples right there.

Following this discussion, I realized why I chose to play guitar and piano with band in a box, using only the midi bass and drums. I only pick styles with acoustic bass and brush drums, or I tweaked styles and made my own.

This way I can “jukebox” a whole song folder (standards, modern jazz...) without once having to change instruments. I can play a whole evening without any hassle or loading or unloading samples. Is nice! This way I have fun playing, like with a band. smile wasn’t that the whole purpose of Band in a Box?

Have fun playing.

Biab, Kontakt, Sampletank and lots of nice libraries, from Fluffy audio to Abbey Road drums.
Check out these great contemporary Jazz Styles: www.jazzstylezz.com