Ah! I spy something I can help with. Get over here!
Last year, I was stuck with the same problem: I knew some classics, but had no idea in which direction to go next. So I've been asking for advice and doing lots and lots of listening.
I've already seen ton of great recommendations above, and I can really second the spiderweb strategy. For me, that was merely the beginning: all great artists evolve and a lot of the albums most of the 'greats' made do not appeal to me.
Lee Morgan is a good example: I'm in love with The Procrastinator, but I can't really get into The Sidewinder, one of his more famous albums. Live at the Lighthouse I haven't even heard yet (it's next on my list!), but Grant Green's Live at the Lighthouse I love and own. And Morgan is not an extreme example: he was tragically killed at a young age, whereas artists like Coltrane, Hancock and Davis have been evolving throughout each decade.
Anyway, without further ado, here are some of my recommendations. I really mention specific albums that are personal favorites, and I've added a short description. I hope you like some of them or discover great ones through the spiderweb strategy. Good luck!
Yusef Lateef - Eastern Sounds (Lateef is an amazing multi-instrumentalist, who plays the saxophone flute and hobo among other things. With this album, he incorporated Indian music into jazz, and I still listen to the result on a weekly basis)
Idris Muhammad - Power of Soul (New Orleans drummer converted to islam and responsible for an amazing string of collaborations and groovy albums. This is one of those spiderweb albums, because it features Bob James (Nautilus anyone?), Grover Washington Jr. and Randy Brecker)
Grant Green - Live at the Lighthouse (Grant Green is one of my favorite artists, and this is one of his most compelling live(ly) performances. The album cover speaks volumes about the music.
Art Blakey & The Jazz Messengers - Moanin (Art Blakey has been running his own private jazz academy for decades, with tons of talented musicians passing through the ranks of the Jazz Messengers. Moanin' is merely an example; there are tons and tons of great albums by this group)
Cannonball Adderley & Bill Evans - Know what I mean? (Simply so pretty that it makes you want to cry. Cannonball was a powerhouse, but toned it down a bit to match Evans' playing style on this classic album)