What did we learn from this trip?
1. Plan for bad weather. Even if it seems highly unlikely, plan for it anyway. We went to the driest, sunniest part of Italy, and got rained on. Next time I travel, I'm definitely bringing a sweater and some form of rain gear. Packing my sweater this time was a last-minute impulse and I was very glad of it on several occasions. Also: plan the trip schedule so you can possibly shift activities around to nicer days (see below).
2. Build in a "spare" day. For us, this was the day we spent strolling around Naples. If necessary, that could have been the Archaeology Museum day. A spare day also lets you devote time to something you hadn't known about in advance. Similarly, don't plan on doing anything the day you arrive. Rest up from your flight, get your bearings, take in the scenery.
3. Refrigeration. This isn't optional for us, as Diane needs a refrigerator for her insulin, but being able to buy breakfast and lunch items at a grocery (at grocery prices) is very convenient and a huge money-saver. (Plus it's interesting to nose around the grocery shelves in another country.) This lets you save up your time and money for big fancy meals.
4. Age nine is old enough for overseas travel. Robert was able to keep up with the rest of us physically, and was interested in the things we saw. Just make sure there's gelato available.
5. Exchange some money before you go. My own bank gave me a very good rate on Euros, and often banks will waive the transaction fee if you've got an account there. It meant that we didn't have to worry about getting cash, or about getting shafted by the currency exchange office in the airport, or when they'd be open, or any of that.
I plan to apply all these to our next trip, when we brave the exotic and possibly hostile wilds of upstate New York. Does anyone know what they use for money there?