We would appreciate advice on how best to go from Naples airport to our accomodation in Sorrento with our luggage in a few weeks. Would a taxi be very expensive? Any advice? Thank you
The easiest way is to take this nice coach bus. €10 per person.
Schedule.
http://www.curreriviaggi.it/autolinee/images/AUTOLINEE_CURRERI.pdf
If you miss the last Curreri bus at 7:30pm, you can also go to the Central station in Naples (by taxi or shuttle bus) and catch a Circumvesuviana commuter train to Sorrento. There is one departing every 30 min at .39 and .09 past the hour. Last one is at 9:39pm.
That is the cheapest option.
The most comfortable option is of course a private car (limo) service from the airport to Sorrento, which should cost you around €90-€100.