Musk just addressed this. Mars has an atmosphere of CO2 and Nitrogen, so we can grow plants, a day length similar to Earth's (24.5 hours), and is larger.
So you can grow plants in some kind of transparent pressurized place... Just like on the Moon.. or on a space station
You can use ISRU and atmosphere resource extraction to generate rocket fuel on the surface of mars, rather than being restricted to the rocket fuel you bring with you.
Ultimately, the answer is Mars has the necessary resources and when you look into the details just makes more sense and is easier.
That depends entirely on the effect in question.
You'd have a hard time pressurizing the moon's atmosphere to harvest it for propellent.
In the long run, there should of course be settlements on both bodies.
A space colony would have much more need to get supplies from Earth.
Once we've learned how to run a space colony on the Moon, building a second one on Mars would be much easier.
None of those problems exist on Mars. Others exist, but you can't just directly say it was easier.
Tourism would be an obvious sustainable Moon industry. That does fit your description :)
I see this as a disadvantage; the major difficulty of space exploration is getting out of the Earth's gravity well. I don't think it's wise to fall back into another one.
The point of the booster for Earth is both to get out of Earth's gravity well and through its atmosphere (both of which are far less of a problem on Mars).
The moon also has a small gravity well, but no real resources to help you escape it. Mars has a bit of a gravity well, but has many more resources to help you escape that gravity well.
Mars' soil contains tons of perchlorate at levels which are very toxic to humans.
TBH Venus seems like a better candidate for long term terraforming.
You can build floating complexes in it's upper atmosphere, and it has enough oxygen and water locked in it's atmosphere and we might be able to fix the rotation and the density of the atmosphere in one go by using the atmosphere to speed up the rotation of Venus. While both of these are quite "far fetched" technically, as far as terraforming goes we aren't any closer to terraforming mars than Venus, and at least for Venus we don't need to figure out how to give it a magnetic field.
https://en.wikipedia.org/wiki/Atmosphere_of_Venus#Induced_ma...
Additionally the current theory is that if Venus will be sped up to below 56h per rotation it would regenerate it's intrinsic magnetic field which should be near earth levels.
And while Venus does have higher gravity than Mars, it's still lower than Earth's, and overall the delta V for venus insertion orbit is slightly lower than what you need for Mars.
That's great and all, but how exactly do we realistically speed up the rotation of a _planet_?
The mass of the venusian atmosphere is high enough for this to actually work and still leave you a lot of atmosphere to work with, it will take 20-30 years but it still doable.
But compressing acidic gasses makes the corrosion problem worse, doesn't it? How do you deal with that?
This is planetary engineering. It's not supposed to be fast.
Unless, of course, you are a Kardashev II civilization.
As far as terraforming goes, Venus is just a better candidate for long term colonization.
Mars is much smaller than Earth. From Wikipedia: "Mars is less dense than Earth, having about 15% of Earth's volume and 11% of Earth's mass, resulting in about 38% of Earth's surface gravity."
Ref: Old man's war.
Of course you want the first colonists to not be sickly, but they won't need to be Olympic decathletes in their 20s. Equipment for lifting heavy objects can be sent more cheaply than people (it can go slowly and doesn't need life support).
I think for a venture like this maturity and patience is going to be more important than physical strength. There will be a lot of tedious tasks with long checklists that need to be followed near exactly to succeed. There will be a lot of disappointment and frustration when things fail or timelines slip. There will be the irritations of being stuck in a small social circle with a few people you intensely dislike but have to depend on for survival.
Add in the fact that your sperm or eggs will probably get exposed to large doses of radiation until they figure out how to get to Mars faster, and it will be far less attractive to anyone who is planning to have kids someday.
in my own personal experience, this thing works worse for older folks, who get territorial, grumpy and so on. But we aren't discussing folks in their 40s, rather 50s and 60s