No such thing as "smooth jazz". It's a misnomer. There is real jazz, and then there's everything else. This so-called smooth jazz falls in the latter category. They started out calling it "fusion", which was an amalgamation of jazz, rock, and R&B. That seemed to be more correct. Even Miles was out there leading the way with "Jack Johnson", "In a Silent Way" and "Bitches Brew". Charles Lloyd, Chick Corea, Eddie Harris, John Klemmer, and Herbie started getting "electrified". It was experimental and pushing the envelope. Then the Larry's came along - Coryell and Carleton ... the Yellow Jackets, Spyro Gyra, Jeff Lorber (and "Fusion" remember them) ... they all started with there own brands of creativity.
I've seen/heard everyone on this list live - with the exception of Jeff Lorber. I like listening to a lot of different kinds of music ... straight ahead jazz, "hard bop", big band, fusion, R&B, gospel, and classical. To me, artists like Dave Grusin, Four Play, Joe Sample, Lee Ritenour, David Sanborn, The Yellow Jackets, and Spyro Gyra all bring something to the table.
Where things started to get really diluted was with Kenny G, and his mall/elevator music that was selling off the charts! Now, all of a sudden you get people saying they like this new brand of "smooth jazz". Then came the Candy Dolfers, Rick Brauns, and Richard Elliots with their syrupy, watered down, everybody-sounds-the-same kind of dribble that apparently appeals to the masses ...(which is the reason that real jazz artists never made any money unless they "crossed over". Think Charlie Parker or Wes Montgomery with "strings"). Put another way, if it's a commercial success, chances are it ain't real jazz.
Well that's my two cents. Have a great weekend, and happy listening to whatever it is that stirs your soul.