What would you do at Ceres if you could get there?

The big problem with Ceres colonization is that it is so far away that it take a big delta v requirement to get there, and what do you do there when you get there?

Taking the first part of that question, you can set up a refueling depot there, then the trip back is simplified greatly.  As I calculated last night, you can land sufficient materials and equipment on Ceres to begin mining its extensive water supplies and use that for refueling the trip back to Earth.

The second part of the answer comes from the delta v's withing the asteroid belt are a lot lower once you get there.  Traveling to other asteroids and mining them becomes a lot easier once you get there.  Look at this delta v table below:

Mission tables

Unfortunately, the launch windows are going to be a bitch.  You may not have much opportunity to visit other bodies in the asteroid belt unless you do it the way they are doing it with the ion engines.  High delta v may be possible if you've got plenty of fuel.  Or perhaps they just took advantage of an available launch window to go to both Vesta and Ceres with the Dawn spacecraft.  The launch window is over 17 years long.  Not encouraging at all!

Perhaps you can go the 20 trillion dollar rock that lives between Mars and Earth?  Those should be more reasonable in terms of launch windows.

Update:

You may be able to get more favorable launch windows by going to Mars from Ceres, waiting awhile, and take off for your destination from Mars.  Or just take off from Mars itself.  Hence, we may have found a use for Mars--- as a mining stage point for journeys to the asteroid belt.  Ceres does not have that advantage, unfortunately.