I think it's more advantageous for humans to spend the time and resources on the planet Venus, than to do anything with Mars. Mars has history significance, but has no future for us. Venus holds the future. The future of Venus is our present. Earth will continue to move away from the Sun, and so will Venus. That means In the future Earth will be where Mars is today, and Venus will be where we are today. Given more time, Venus' atmosphere will evolve to one like ours today, it will thin out and temperatures will cool on the planet. Venus is our future, and Mars is ancient history.