Don't forget the "Steamin'" series and of course, "Birth of the Cool". "Sketches..." is one of my favorite sit-down records along with "Kind of Blue". I really dig Bill Evans too (Get it?).
Also, great records: "Milestones" and "No Blues". If you're into collections, then "The Complete Bitches Brew Sessions" is a must have. The "In a Silent Way Sessions" is up there too.
If you're thinking of Coltrane, of course everyone will recommend "A Love Supreme". But I say check out: "Afro Blue Impressions", "Crescent" and "One Up, One Down: Live at the Half Note". "One Up, One Down" is seminal, up there with "Kind of Blue", IMO.
A tangent, but related, is "Footsteps of our Fathers" - Branford Marsalis Quartet. An amazing recording on many levels.
Could go on and on...