Venus' cloud cover is above 10000 feet. That's well beyond the human comfort zone. (I mean, you could live up there, but you wouldn't be able to operate at nearly the same level. And if you have to go above 17000 feet then your body is slowly dying anyways, without external oxygen.) You'd need to burn off and replace huge portions of Venus' atmosphere to make it habitable. Possible in theory, mirror arrays and comets, but crappy.
For terraforming, this is perhaps true, but the big iceball moons currently represent an easier prospect for simply living then Mars does. Abundance of easily converted water ice. Mars has lots of water but it is harder to make useable, being trapped in underground permafrost or aquifers.
Ice is also easier to dig through, and if you want to move somewhere without a nice active magnetosphere, living underground for protection from radiation and for the insulation is pretty much de rigour
edited 25th Mar '12 7:57:26 PM by Night