We have an 8 hrs connection at FCO (8:45-16:30) - the original idea was to have a hearty lunch somewhere in Rome and revisit some old favourite sites but just realised that Roman lunch-times are rather later than what we are used to. I think that we'd need to start back to FCO around 2 pm to avoid any stress.

So what is the general consensus - would it be better to have some 4-5 hrs in the city, with lunch probably replaced by several cups of espressos in, say, Piazza Navona OR head for Ostia or similar nearby place (where?) for a peaceful day out?

I know it's personal preferences, so if I'd have to rephrase - "what nice things there are to do/see near FCO?"