I go there often but most on business maybe too high a price list, however,did go with the family last summer and you can have many nice meals if go away from the coliseum area (forio imperiale), overtly touristic.
for the famous italian gelato without breaking your bank go out to Il Gelato di Procopio, Via XXI Aprile 23, right by piazza Bologna with metro and bus, from there you can take bus 62 anywhere in rome and takes you to the Vatican.
Gran Cafe Cavour, Via Cavour, 290 right behind the castel san angelo near the vatican the bridge takes you to it and back into city center Rome with plenty of shopping and resto area.
L'Archetto,Via dell'Archetto 26, right near the trevi fountain (now Under renovation with scaffolds) but its a great spaghetti place
and this is a chain, very nice place right in the middle of Rome shopping near Alberto Sordi shopping mall
Rustichelli & Mangione, via tomacelli,14
Rome is vibrant, lotd of emphasis on foot and walking, only a bit too old buildings ::)
hope it helps your planning