I had an absolutely wonderful time at Grazia&Mauro's place. Self-contained loft, spacious, with an amazing terrace from whcih you can view (almost) whole of Napoli. The location may seem a little bit hard (uphill 15min walk from centre) but it's worth it. Also you can take C63 bus from Dante or Cavour and then it's just a minute walk to the building. The hosts have been kind and responsive, so were the cats!
For my fellow vegans, two great places to try:
Isabella de Cham has a wonder of a vegan pizza!
Vegan Art by Sbuccia e Bevi - home made tea, bread, seitan, burgers, and even traditional babá!