I've always thought of Sazed being 6' 7"ish (with Vin being 5' even (easiest, since she tells you it multiple times), Kelsier 6'3-4", Elend 6', etc), with an Asian skin-tone and facial structure (maybe Amazonian tribesmen, that seems to fit; I'm trying to think where I got my idea of him from...), combined with the elongation of limbs due to his castration and his thin build, would make him seem much taller than he really is. This is especially evident when you conisder that the average adult skaa male is probably 5'8" (or shorter), with nobleman maybe hitting 6'. We are thinking of our age, where the average human male is around 6' tall (plus or minus a few inches), when being 6'7" is an impressive height, but not freakishly so. This also puts Kelsier into perspective (if we base his height near my guesses), since he is close to a foot taller than the average skaa, taller even than nobleman, making him seem greater than a normal person. The spread of a few inches also fits Sazed's slight unease at standing near someone almost as tall as he is (can't remember what page it's on, but it is in FE somewhere...)
When he is fighting the koloss in WoA, the koloss is surprised because Sazed is even more muscular than the koloss itself, not because Saze is as tall as it (no Feruchemical metal that has been revealed will let you do that, I believe.)
Also, first post!
Prepare for much flinging of random/not-so-random ideas; I'm chock full of them!