Plan one big thing per half-day
Colosseum, Vatican Museums and Borghese Gallery are intense. Do not combine two of them on the same morning with small children. Add squares, fountains and short food stops instead.
Strollers: where they work
Villa Borghese, Piazza Navona, Pantheon area and river walks are manageable. The Forum, Palatine and many cobbled lanes are difficult. A lightweight stroller or carrier is better than a large pushchair.
Reliable breaks
Use Villa Borghese, the Orange Garden, department stores, large museums and fast-food toilets as reset points. Refill bottles at nasoni fountains and keep snacks ready for queues.
Best family zones
Vatican/Prati is easier for wider pavements and food; Villa Borghese is best for play; Trastevere works early evening but gets crowded late.