I agree with Bill Evans and Keith Jarrett rec's - they'd be at the top of my list (though Jarret's grunting sometimes gets on my nerves). I like Keith Jarrett - "Standards" (there's no grunting :-) ).
Others that I have and like are:
Chick Corea - note that he has some acoustic stuff and a lot of electric fusion stuff, so it depends on what you really want. For Acoustic check out Chick Corea/Gary Burton - "In Concert: Zurich Oct, 1979", and Chick Corea/Dave Holland/Barry Altschul - "A.R.C."
Don Shirley - "Solos" and "With 2 Basses" I like them though I don't know if this is his best stuff
David Chesky - "The Tangos and Dances" I really, really like it. Just one note - it's very mellow and I often fall asleep during it. In fact when I want a nap, this is one of the cd's I put on. (I know this is hardly an endorsement, but trust me it's worth having)
Also mellow - Tord Gustavsen Trio - "The Ground" and "Changing Places"
for something with vocals - how about Tori Amos? and Diana Krall?