In the 80s Woody's band did some jazz cruises on the SS Norway- they were produced by Hank O'Neal of Chiaroscouro Records.
They were lots of fun- in addition to playing our own sets, we backed up players like Dizzy, Clark, Al Cohn, Jake Hanna, Cab Calloway, Joe Williams, Mel Torme and many others. It did provide an opportunity to spend time up close & personal with these artists (you should have seen Dizzy puttin' away the BBQ), plus we would hang with crew members who knew some great "insider" spots on the ship and in the various ports (away from the touristy stuff). A week or two was plenty, though- I don't think I could stand to work on a cruise ship. If you are an employee there are all sorts of rules to keep you separate from the passengers.
I think this Mosaic cruise would be big fun, just a little too pricey for me.