We stayed near the Pompei ruins, was during August and the weather was very hot, whatever you do, DO NOT DRIVE, when you get there you will see why, every car is a wreck, the driving is worse than appalling.
Pompei is large, but is fascinating, then visit Herculanium it is so well preserved, it's mind blowing.
Sorrento is beautiful, as is Capri , the ferry to the island goes in the morning and returns in the evening, take a taxi up to the town, it's a hell of a walk in the heat, also do the trip up to Vesuvius, part way up in a Unimog bus, then walk the rest, the views are amazing.
For getting around the coast the circumvesuviana railway from Naples to Sorrento is good and inexpensive, if you go to Naples keep your wits about you, the risk of being robbed is very real, even in the railway station, I lost count of the number of ipads & mobiles we were offered.