I like my jazz with lumps in its gravy. I don't really care too much for a lot of what gets classified as "smooth jazz" (Brubeck transcends, however). Mostly its just the stuff they play on the radio that bugs me - too safe, clinical, boring. Guess that can be said for a lot of radio, though.
Here's some mellower stuff I like...
Ben Allison:
Keith Jarrett:
The Bad Plus: (an Aphex Twin cover
- these guys cover other unexpected stuff like Pixies, Sabbath, etc..)
Select era of George Duke: (check the young Alphonso Johnson! also young Scofield...)
Brad Mehldau, Ahmad Jamal, Joshua Redman, E.S.T. come to mind too.