There is definitely merit to targeting university towns. University students seem like they're more likely to be in their demographic. Most of the time they will want smartphones, long distance calling, and data plans, but they will also want the cheapest options. They usually won't leave town often, other than to go home, so they can live with island coverage. They don't usually rely on their phone for critical calls like a business user would, so they can put up with some network deficiencies. And they are far more likely to influence their parents if they have good experiences than the other way around.
New immigrants also fit many of these characteristics, but they are pretty much out of potential expansion areas which include large numbers of new immigrants, while there are still plenty of university towns.