Just got back from my trip and I had a couple tips before I get back into reality and forget.
Early morning departures: I had planned on taking the first train to the airport, which would have given me a couple hours before the flight. But the owner of the apartment I rented let me know that the train may run that early, but buses to the train station would not, and it's be a half hour walk to the Trastevere station. He didn't think much of the area around the station that early in the morning, and I didn't think much of a half hour walk with a suitcase that was a lot heavier than when the trip started. He arranged a driver to pick me up at 5:15, which got to the airport in plenty of time. Hardly anyone is up that early.
Heavy stuff: Books are heavy. That paperback museum book seems lightweight until you buy several of them. Think twice about buying books. (I'll forget this rule before the next trip).
Getting up early: Actually, not a lot of people (tourist people especially) are out before 9. If you can go to the Pantheon by 9, it's a much nicer and more peaceful place. It's beautiful anytime, of course, but mornings in Rome are lovely. Even the food vendors in Campo dei Fiori are still finishing setting up around 8:30.
Water: Rome has water fountains everywhere. Maybe technically just "fountains", but unless it says otherwise, it's probably potable. They even have a couple bottle filling stations that spit out natural or fizzy water (one by the colosseum and one outside the Vatican by Cipro metro station). So very civilized. You know where they don't have water? The airport. Not a single drinking fountain could be found. Their sink water is still better than drinking fountain water in London, but still. Given the emphasis on refilling bottles and not wasting, this could be made easier.
VA refund: Best part! It's easy. I was transferring through another European city, but thought I'd try to get the stamps here instead of hassling with it later. The people in front of me in line were doing the same, but were actually told to get the stamp in Italy. If you're carrying on, go through security, and immediately after before going to the gate and passport control, look right and find the line. It's even open at 6am. The line took 20-30 minutes to get through although it wasn't really all that long, so plan for that. Maybe some people didn't have their forms already filled out? It could be a pain if you get behind a tour group, but hopefully they'd be checking their stuff and would deal with this outside security. There are signs on the office that make it clear- No Items, No Stamp. But this guy wasn't checking items. Then they have the mailboxes right there for the different tax refund companies, and no stamp needed if mailing from the EU. Not sure the places were open if you want to get cash back, but I'd rather have the refund on the credit card. Now to wait and see if it actually happens!
And another couple things- Car rental returns at FCO. I had returned a rental here a few days before spending time in Rome and it's not bad at all. Just follow the signs to Car Rental Return. Following signs is probably easier than listening to any GPS, which I found to be true through most of the areas I went. It was quick (ish). Then train into the City. Validate as soon as you go through the gate to the trains. You don't want to walk to the end of the train for a seat and then remember you have to do this, because the only validation boxes I saw were near the entry.
That's it, for all the travelers who like having details before going.