Rick suggests Monetti Taxi. Has anyone used this company and what can you tell me?
My wife and I just booked the Monettis for an 8 AM-6 PM private driver in July to help get us to our desired places along the coast (as far south as Paestum). Was 300 Euros, total--certainly not cheap for one long day--and while we haven't had the tour yet, I can say that the booking process was a pleasure with this family-owned business. When we compared the time to be lost on the bus (and waiting for buses, which are supposed to be packed in the summer), we bit the bullet and splurged. Ordinarily we like to travel on our own via foot, bus and train--closer to the local culture in lots of ways--but with just one day to see Amalfi, this made sense.
I think your doing the right thing but we hired a private car and driver for much less for the same type of tour and the same length of time. If you would like to send me an email I will provide some information to you.