We used this blog post when we were there last year http://www.italylogue.com/featured-articles/top-10-things-to-do-in-naples.html
The underground tour (#7) was excellent and comes highly recommended.
As for Pizza, we ate at Pizzeria Di Matteo as mentioned: it's a crush and there's no queue and nowhere to sit ... But the pizza was delicious and the experience authentic.
;-) enjoy about 5 years ago
Da Michele by far! After living in Naples area for 3 months I've tried several. You really can't go wrong strolling down "pizza street" in the old center (by the aqueduct museum- also a GREAT museum). Be warned as some pizzerias don't open until 8pm on weekdays! about 5 years ago