There's a fuss? I must be out of the loop...
Similar to mtrycraft's post, ideally you'd like the height of the tweeter as close to ear level as possible. Not a complete necessity, but that's the idea behind using speaker stands.
As for what you fill them with, I think it's more important from a stability standpoint than it having anything to do with an impact on sound reproduction. Last I checked, speaker stands didn't have any specs from their tests in anechoic chambers...

-TD