Town or Beach
Skiathos is a small island with really only one main road that runs from Skiathos town along the south coast to Koukounaries (one of the most popular beaches). The route is well served by a very regular and cheap bus service that stops at all the numerous coves / beaches on the way.
If you are going to Skiathos, there is a choice to be made.
Either stay near one of the beaches (all of which are relatively small 'resorts') and travel in to Skiathos town in the evenings for the numerous restaurants, bars etc (Skiathos town is very picturesque with a pleasant atmosphere - at least in September that was so. In high season, it is very busy I understand).
Or stay in town and take the bus to the beaches during the day.
We did the latter and it suited us.