day tour to naples from sorrento

We didn't take a formal tour, we simply took the Circumvesuviana (local train) from Sorrento to Naples - takes about an hour. They are frequent, usually every 30 minutes. Costs 4 or 5 Euros. In Naples we visited the Archaelogical Museum, which was very good - allow maybe 2 hours. In the old central part of Naples (called Spaccanapoli I think) there are lots of interesting shops and some very good restaurants. We had lunch at Bellini's which was great. Some people think that Naples is not safe but we had no problems at all, and the people were very friendly. On the return trip (or vice versa), consider taking the boat back from Naples to Sorrento. Costs around 15-20 Euros depending how fast it is.
Hope this helps, Greg.

thanks, Gregg-good advice
the "tour" groups are pricey appreciate your input

Naples is definitely worth visiting, so if you are only comfortable with a tour, it's better than not going at all. I did it just on my own, relying on public transport - had no problems. It was chaotic but I got used to it and enjoyed it a lot. Great food and espresso, as well as gorgeous churches and lovely convent overlooking the city and the bay in the Vomero district (Certosa di San Martino)