Common usage indicates that "than us" is just fine. Remember English grammar doesn't come from a grammar book - grammar books are merely imperfect attempts to describe common English usage.
Carl Sagan did, I recall a quote of his talking about the composition of the brain and he says something along the lines of "to consider that we live in a universe which permits the construction of biological machines as intricate and as subtle as we"
EDIT: These downvotes confuse me. It is a matter of fact that there exists an entire non-trivial linguistic school of thought which holds a belief completely incompatible with what GP just presented as more or less indisputable. GP's authoritative tone is unjustified, regardless of which camp you happen to agree with.
