The Quartieri Spagnoli are quite uphill, so you will have already prepared the calories burned for what I suggest you do now: treat yourself to a nice fried pizza at Sorbillo! Just thinking about it makes my mouth water, so much so that I would take a plane to Naples just for HER. The only flaw, but you'll have to get used to it in Naples: it's strictly take-away only. There are very few places in Naples where you can sit down to enjoy something quick.