If you like these guys and Pink Floyd, you should definitely sample some Porcupine Tree, particularly Stupid Dream and Lightbulb Sun. Trippy prog-rock stuff. In later albums they get more metal-y. Next week they're releasing an album that contains one 55 minute song.
Though, The Sky Moves Sideways and Signify (and Up the Downstair, though I haven't heard it) both sound more like Pink Floyd. Hell, TSMS is structured pretty much exactly like Wish You Were Here. I like Stupid Dream and Lightbulb Sun more, but they almost sound closer to 90s Radiohead than Pink Floyd.