I too am confused by the question. I believe this genre (as far as hardcore listeners are concerned) is rather straightforward as far as instrumentals go--my simplest definition would be contemporary instrumental music with jazz elements. Many on this board, to include myself, have complained that Smooth Jazz has been its worth enemy over the years by incorporating music (overplayed R&B and A/C Vocals) that eventually drove away the base listeners who carried and embraced the genre to begin with. Vocals are a dilemma, there is no question about it. Familiarity can at times breed contempt (A/C crossovers and overplayed cuts by Phil Collins, Barry White, George Benson, et al). As far as my personal experience is concerned, since I launched in July 2008, those "diehard" listeners I refer to largely prefer an instrumental-heavy format. But what I am finding out is that more "casual" listeners prefer to hear far more vocals than I typically play. But I am not about to sacrifice my beliefs about where the format "should" go to boost my own numbers. In the end, I am loyal to those who are loyal to me and listen for several hours each day. And if my listeners want to hear more instrumentals, that's what they are going to get. As a hobby broadcaster, I have the luxury of doing that.
My basic approach is very similar to darksoldier's. I have about 3300 cuts in my rotation, but I have them categorized so that certain ones play only certain times of the day. New releases get more airplay, but I too prefer not to beat listeners over the head with them, and I ONLY play ones that fit the overall sound and programming strategy for my station. I also usually like to roll out deeper cuts in addition to the ones the labels are promoting. I also try hard to find the best new music from Indies and lesser known artists as well. My strategy is no different for dated NAC cuts. What I think are the best ones get enhanced airplay, but I do make a concerted effort to avoid those which have been overplayed, opting to go deep on albums.
By no means am I suggesting my strategy is the model for the future (to be honest, the future looks pretty bleak the rate we are going). I am just following my heart as one of the aforementioned "diehard," passionate listeners who refuses to let go of this music and the vibe that attracted me to it over 20 years ago.
Well stated as always Chris. We may both be wrong at the end of the day, but I don't think so...
Now back to the followup question. In terms of the sheer number of songs within the genre, let's just say that there are a plethora of songs, likely comparable in number to any other genre within Smooth Jazz, or songs that based on who is programming fit well within the mood or feel of a programming strategy. As an example Alan Kepler feels that The Manhattans, Ace, and EWF fit well within the genre.
Everyone else I know who has spent more than 10 minutes in the genre disagrees...
Hate to quote the late Michael Jackson, but here goes..... "The worst thing you can do is think about it. You have to feel it."