Planet of the Apes and The Andromeda Strain are definitely the two films that to me best exemplify the type of "similar to 2001" Sci-Fi movie Harvey asked for. Neither one is as awe-inspiring as 2001, but both are the same type "big-budget, epic, leisurely paced, abstract and philosophical Science Fiction film with no explosions, space battles or other spectacular devastation" as 2001.
But PotA had plenty of violence -- abductions, shootings, brutality, lobotomies, deaths both accidental and deliberately inflicted, you name it.
Hmm. Violence wasn't in the list. As we mentioned earlier, 2001 has a maniacal computer that kills a guy, cuts off life support to three more, and tries unsuccessfully to kill the 5th guy before he's able to shut it down. Also has some apes beating up other apes.
Likewise, Andromeda Strain features an entire town (with the exception of an old man and a baby) getting annihilated by a space virus.
Still, all three are pretty tame compared to recent blockbusters, including the remake of Planet of the Apes (which features an all-out war between the Apes and the hunter-gatherer human population).