Hmmm. I've already lived my epic day in Rome, and it was like the few days before and few days after. The delicious routine we established in February 2017 was almost like I lived there...
Apartment window overlooking the Campo de' Fiori, at about 6AM I could hear the daily vendors dragging their stands and carts across the cobblestones to set up for the day. That sound and their catcalls to each other woke me up. I dressed for a brisk walk, wife still asleep, and ambled down towards the Tiber, walked along the bank for a few minutes and doubled back around to my favorite tabacchi shop, which also had a coffee bar for my morning espresso & cornetto. The barista knew me the second day.
Back to the Campo, wife up now, we walked downstairs to the market and bought strawberries from Basilicata, blood orange from Sicily, various rolls & cheeses. Made cafe Americano with a Lavazza shrink-wrapped block of coffee through a Melitta filter. And the daily question, 'what do we want to do today?'. Fortunately, rain was never in the forecast--amazing for winter in Italy--and temps were 40-60, so as long as I had my laminated bus/Metro labyrinthine schedule, we could figure out how to get there, which usually included going through Termini station! I'll give you three destinations not usually in the tour books:
1) Baths of Diocletian/Roman Museum-- in plain sight across the street from Termini, amazing structure showing how ancient Romans conducted business, along with all classes of Romans as well. The adjacent Roman Museum has artifacts from the 11th century BC, I believe the Bronze Age.
2) St. Peter in Chains (San Pietro in Vincoli) -- very cool sculptures
3) Villa Torlonia -- up via Nomentana from central Rome towards the north, this is a mostly-abandoned small estate that Mussolini owned & lived in before and during WWII. You could almost see him, arms crossed, on one of the balconies.
Just an example of our daily activities, all usable with the weekly bus/Metro pass, 24 Euro in 2017. And I could find 'deep dive' attractions like these for weeks, and still not scratch the surface. We'd maybe grab a pizza slice or take-away panini somewhere along the way. Late afternoon, the 'dogs' were tired and we'd return to the apartment for usually a 2-hour nap before heading out for dinner around 8PM.
There are a multitude of high quality, unsung trattorias within walking distance of the Campo, and we stumbled upon a couple of great ones--Elle Effe, where we walked by during the morning, saw the owner outside and chatted him up. He's from Catania, Sicily and his cuisine reflects it. No-cheese Sicilian thin pizza with anchovies, black olives and red pepper flakes was unique. Then--upon a recommendation from columnist Katie Parla--we found the Roscioli family's Ristorante Emma for signature spaghetti alla carbonara and 'only in Rome' puntarelle salad, chicory greens served with olive oil, anchovies and salt. Fantastic.
The evening would wind down with a stop for gelato at any choice of top class joints along the way. Crema & riso flavors were my favorite, and an evening walk around the square, as the young adults were just gearing up their nights. And then we'd retire to the apartment...to sleep and do the same thing the next day, with different attractions of course.
You've been to Rome before, so whatever floats your boat to make it special will work--you have a blank canvas. For me, for us, the joy of pretending to live in Rome, if only for a week, was our sweet spot. We hope to do it again, for at least a month, during a winter very soon.