The second-actually-third trip was Rome: because there is a reason for the clichés to be, right? Unlike Paris, I had never been to the Italian capital - Rui did, and he knew what to do and what he wanted to show me.
Of course, we had not yet fully learned that we are more or less anti-museums, and we lost hours in the Vatican (in the Xpress version direct to the Sistine Chapel, but still...), but it was just one more step in our learning curve. If I had to leave you with only one piece of advice for Rome, it would be this: put on some good shoes and go stroll through Passeiggiata del Gianicolo, because you'll be rewarded with a lovely, almost deserted walk and some of the best views of the city.
As I have room for more, I'll tell you to take the opportunity to see all the nooks and crannies of the city, which is a real museum in the open, and that's what makes Rome one of my favorite cities. To do this, it is absolutely imperative that you do not set foot on any public transport, as long as you are in the center - yes, you'll walk a lot (a lot!), but it will be worth it.
Forget the map, use the Tiber as a reference when you need it and walk from piazza to piazza, and from fountain to fountain (the water is safe and brilliantly cold), as long as you have the energy. Get in the churches you want to go, go check the streets you want to see, and, if the weather is nice, sit on the floor when your feet cannot stand any longer and watch the commotion of this city where you hardly see Italians. Rome is like this: hard on the body but a balsam on the soul.
Flight (round trip, per person): 127 euros (TAP)
Accommodation (per night, for two people): 105 euros