Personally I have always found the behavior of city/town names very inconsistent in Basecamp and Mapsource. And it is very different on a Garmin Handheld. The Garmin Nuvi series also different.
There are a whole bunch of different MP_TYPEs for cities and towns, I have tried a variety of these and played with zoom levels, but sort of came to the conclusion "it is what it is".
A specific problem in Mapsource/Basecamp is that the city ICON will show, but there is no label. This doesn't usually happen on the GPS devices.
IIRC, Mapsource and the PC version of Basecamp allows you to choose the font and size for map objects (ALL objects though, not specific types of objects). However the Mac version of Basecamp doesn't give you any control over font/size and the default is really small and can be hard to see in a cluttered map. I think the color is always blue and that cannot be changed either.