We arrive at Naples International Airport at 6AM and have 4-5 hours until our shuttle to Praiano. What would you suggest we do/is open at that hour?
Thecairport has a good selection of restaurants. If you could communicate clearly with a taxi driver to give you a driving tour of the city, I would do that. Check flat rates for Naples taxis first! Or find a private tour driver.
You might not want a taxi tour of Napoli with a tight timeframe, even though the airport is close to the city.