Surprisingly, the moons of Jupiter are one of the worst places in the solar system to have a settlement, especially if it's a waystation to somewhere else. The reasons aren't entirely obvious.
The difficulty of getting to Jupiter
The moons of Jupiter are hard to get to, not only because you have to do some significant climbing out of the Sun's gravity well to get there, but because you also have to contend with Jupiter's large gravity well.
Missions are fundamentally limited by the Delta-V needed to go places. The higher the delta-V, the more fuel you need relative to your payload mass to get to that place. This relationship is exponential, which means it scales badly.
For instance, if you are using $N_2O_4 / UDMH$ as your propellant system (widely used in deep space missions for its reliability), for every 2319 m/s you add, you have to double the size of your rocket, while keeping the mass of the payload constant. Jupiter's outermost Galilean moon, Callisto, requires a delta-V budget of 14170 m/s to get there, which means your rocket (assuming you already started in Low Earth Orbit) needs to be 69 times bigger than your payload. And it gets worse the further in you go. Landing on Io requires a delta-V of 19470 m/s, which translates to an eye-watering ratio of rocket-to-payload of 336. If you want to transport 8 ton worth of supplies, you'd have to use a rocket the mass of the Saturn 5 that was already in Low Earth Orbit.
The problem with fuel depots
Another counterintuitive thing about orbital mechanics is that fuel depots don't provide much help at all. Not only does making a mid-trip 'pit stop' increase the overall fuel you need to expend, but it also drastically increases the trip time.
On earth, we're used to expending a certain amount of fuel to go a certain distance. Fill the tank up and you'll get 100 kilometers closer to your destination.
This doesn't happen in space. There's no friction. A certain amount of fuel will get you to a certain speed. All objects in the solar system have their own orbits, including your spacecraft. Whenever you fire up your engines, you change the orbit of your spacecraft. In order to go to another planet, you have to get your spacecraft's orbit to match up with the planet's orbit and your spacecraft's position within that orbit to match up with the planet's position in that orbit.
The easiest way of getting to another planet is by doing a Hohmann transfer. There are other quicker ways of doing a transfer, but they cost a lot more fuel.
One of the peculiarities of Hohmann transfer orbits is that going from A to B to C costs more fuel than going directly from A to C. It also takes significantly more time, because you effectively have to wait for two launch windows, one for A to B, and one for B to C. Perversely, the launch windows become rarer the closer two orbits are to each other, which means the more fuel depots you cram in between two planetary orbits, the longer it will take to reach each one in order. The frequency of these launch windows is the inverse of the Synodic period.
There is an Earth-to-Jupiter launch window every 398 days. If you had a fuel depot at, say, 2 AU, you'd have an Earth-to-Fuel Depot launch window every 565 days, and a Fuel depot-to-Jupiter launch window once every 1352 days. Unless you timed it specifically for some rare Grand Tour, you'd be waiting an average of 2 years for the planets to align again to start the second leg of your journey.
Other problems with Jupiter
The radiation mainly. Jupiter's magnetosphere is huge, and does an excellent job of funneling a lot of nasty radiation into it's vicinity. The moons of Jupiter are not a healthy place to live, even by the standards of space.
The most likely places to see colonisation in the coming centuries are the Moon, Mars and its moons, and the near-earth asteroids. Those are the destinations with the lowest delta-V, which means those destinations will see the greatest ease of travel, trade, resource gathering etc. I wouldn't be surprised if there were eventually colonies around Jupiter, but I would be surprised if they were anything more than research stations akin to the bases on Antarctica.
(All delta V values pulled from here.)
