We found naples generally very reasonable for a coastal city. It is a more working class city as you say. The worst thing was constantly being ripped off by the taxi drivers and shop around for tours as they are mainly aimed at the cruise ship clients and are crazy money. We booked ours through viatour.com and they were good value.

Pompei, Herculaneum and the Amalfi Coast can be done by train very easily is you have the time. Take the time to walk up Vesuvius as well it has some great views.