There are 8 of us - would it be better to hire a private boat to take us to Capri for the day or take the hydrofoil? Any recommendations for boat companies?
Jan, I wouldn't bother hiring a private boat, as it's an easy trip via the local Boats that have scheduled runs and I doubt that you'd save much / any time. If you walk down to the docks in Positano, you'll find a number of small ticket booths (on the right as you're facing the water). I can't recall names of particular firms, but they all seem to offer similar service. Pick one and buy your tickets. Be sure to note the departure time of the last boat back to Positano! As I recall, there's information on these in the Italy Guidebook, but I'd have to check for the specifics. The boats typically back into the dock, and then a ramp is lowered for passengers to board. When leaving Capri, be sure to allow lots of time for the trip from the town back down to Marina Grande. The Funicular is often VERY busy in the late afternoon. You might consider using one of the open-top Taxi's, as the trip is very pleasant and that avoids the rush at the Funicular. Happy travels!
Jan, I would stay in Positano! We've been to Positano a couple of times for a few days each trip, and loved it. We felt we needed to take the boat trip to Capri, and did so last visit. Capri was okay, but Positano is BETTER. Stay in Positano and see more of it. You won't regret it.