We stayed in the Hotel Barberini just outside of Barberini metro station, and ate in one of the many restaurants up the Via Venuto - there's quite a few there, mostly with outside 'conservatories' where you sit and watch the people (or the traffic...) - still, quite nice in dark evenings for a reasonably romantic meal.
Piazza Navona is very touristy, but again the restaurants on the Piazza itself, and just off it, are pretty good and worth doing for watching people, street entertainers etc.
But, if you're after ice-cream then you *really* have to find Della Palma (sp?) just off one of the roads from Pantheon!!! So much choice, so little time!!!