I love a City break and enjoyed Rome, I don't think I could stretch to more than 3/4 days but a mate of mine went for a week with his Mrs and I think they must have visited every church in the City.Villa Borghese is great for a stroll and for its beauty. Better in Spring and more so in the summer.
Campo dei fiori and piazza navoni are great hangouts and very close to major attractions.
Bit further is a view of the City from the top of Castel St Angelo and walk around over Bridge St Angelo.
Via del Corso is great for a long stroll and shopping. Fantastic Diesel store if you like your denim.
If you can experience walking into a fresh pastry shop when they first open around 6 am ish it’s amazing. The pastries mama mia, per amore!
Thin pizza slices a plenty and amazing. For food check out the area of trastevere. Great food and away from the busy touristy hot spots.
Wish I’d have had your info before I went, personal choice but I preferred Barcelona over Rome, both have some great attractions but I think the people are friendlier in Barca. Also prefer Spanish Tapas over pasta and pizza.