If you're not in psychedelic music then you probably won't particularly like Piper At The Gates Of Dawn (Out of the Syd Barrett songs I've heard, I like Astronomy Domine best). You might like Saucerful Of Secrets better, I'd recommend listening to Set The Controls For The Heart Of The Sun which is quite laid-back but in slightly chilling sort of way, definitely Roger Waters' own style rather than attempting to imitate Syd's.
I'd also recommend Atom Heart Mother, the title suite certainly isn't an easy listen but I think this is the album where the 1970s Pink Floyd sound really starts to form - Meddle is the album where it comes together with (mostly) superior songs and more focused compositions, but you can definitely hear where Echoes comes from when listening to the AHM suite, Fat Old Sun is a nice Gilmour piece, If is definitely Floyd (and is notable for Waters' first lyrical references to insanity) while even Alan's Psychedelic Breakfast has their sound - Sunny Side Up is musically similar in feel to A Pillow Of Winds, for instance. Only Rick Wright's Summer '68 truly has no relation to the albums that followed.