Forget Mars
Venus is where it is at. The high pressure on the surface will make, creating energy a cinch. Energy is created from gradients and that planet has loads of them. Carbon Dioxide is a pain you say, we will be experts in dealing with it in a few years. I say, lets start with some heat resistant cyanobacteria and algae.
Hate the long days, lack of magnetic field or backwards spin? Stop your complaining! The ease of Mars is the reward of dusty boredom.