Fodor's is one of the premiere travel information publishers in the world. If you are going to be traveling with an iDevice of some kind during the tour, it's worth your time to download their FREE Rome Travel Guide. (Click here to preview it.) Your parents are used to carrying large/heavy Fodor's Travel Guide books on vacation. You can carry it all in your pocket!
If you are not using an iDevice of any kind, but would like to do some great research prior to departure, the same information may be found here, in a web app.