We went to italy last year, to San Remo, Milan, Venice, Florance and Rome with a day trip to Naples and Pompei. I would definately reccomend at least 4-5 nights in Rome. San Remo is a very relaxing beautiful place right on the mediteranian sea, not much to do there but very nice for a 1-2 night relax away from the hustle and bustle. I would definately recommend Venice (2-3 nights), for the experience especially with a 11 and 13 year old-they would be fascinated. Overall we found Italy to be great, beautiful food, beautiful culture and very friendly.