Some well known postrock (ish) acts I've enjoyed and seen live over the years …
Godspeed
Explosions in the Sky
Matmos
Talk Talk
Mogwai
Gastr del Sol
Stereolab
Broadcast
Tortoise
Talk Talk's album Laughing Stock is one of those must listen albums, it's a bit of a cliché but it's fucking good. Spirit of Eden too. Godspeed's earlier stuff is terrific. Stereolab's earlier albums like Mars Audiac Quintet, Emperor Tomato Ketchup, Peng!, Transient Random Noise Bursts With Announcements …
Mogwai are probably the most enjoyable postrock group I've seen live, probably because their songs are of a manageable length and they don't have too much quiet time. Their Perth show in 2009 was hypnotic.
I listen to a fair few practically unknown Australian postrock artists … Eleventh He Reaches London, Craig McElhinney, Hooper's Store, Raven, The Television Sky, but they're a bit creaky a lot of the time.
Someone reminded me of this awesome track earlier today: