Work off Corso Vittorio Emmanuele II when in Rome. It runs from The Vatican down towards the Colosseum, with stuff like the Trevi Fountain not that far off it.
There is great food all over the place, at good prices when you wander off the main tourist routes.
The shopping wasn't much good, so I wouldn't spend much time wandering round the designer bits.
Get yourself some weed before going to the football so that you fit in with the locals.