Day trip to Capri.

I would make a day trip to Capri only if you're basing yourself out of the Naples area (better yet, if you could spend the night). Capri is meant to be very leisurely and relaxing. Coming from Rome, you'd have to time the train and ferry - it would make for a very long day. There is plenty to do in Naples for one day (and more) if you want to go there from Rome (but of course it will be a different experience than Capri).

Voting with Agnes here: Capri is best if you can give it enough time to enjoy the off hours when most of the day-trippers have gone or haven't yet arrived. That would NOT be accomplished as a long, multi-transport day trip from Rome. You need to stay overnight on the island for a quality experience.

I agree....needs at least one night on the island to thoroughly enjoy. Take a ride in an antique convertible taxi (you will be glad someone else in driving), visit Anacapri (the very top....views are incredible). Enjoy a room with the view of the Faraglioni. Go to the Blue Grotto (disclaimer: we did not get to do that, but friends did this past year, and they loved it and returned with fabulous photos).

But, if you are truly limited to just 5 days in the general area (if one of those days is a fly-in day from the states), that might be pushing it to dedicate an overnight to Capri. I might suggest (instead) traveling along the Amalfi Coast (with a driver) all the way too Ravello, and then take a boat back (I can't remember which city offered the return ferries, but not to far from Ravello. Seeing the coast from land, and then from water makes it extra fun, as the views are very different (and each beautiful).

But, if really comes down to what you want to see/do. For my husband, Pompeii was a MUST.