cg,
"Now I just have to convince my husband on the trains. He likes the flexibility of a car and coming and going at our pleasure."
Your husband is likely thinking in North American terms. In many locations in Italy (and elsewhere in Europe), a car is simply not needed as the public transit is frequent and cheap. You'll probably find that in Bellano and other parts of Italy, you won't need to be "coming and going", so a car will be of little value and will sit in a car part, gathering rental charges and parking fees.
Keep in mind also that EACH driver will require the compulsory International Driver's Permit to drive in Italy, which is used in conjunction with your home D.L. You'll have to be conversant with the dreaded ZTL (limited traffic) areas (hefty fines for violations), tolls on the motorways, automated speed cameras and the Traffic Tutor system which also responds to average speed between two points, high fuel prices, compulsory CDW and unattended fuel pumps which can ONLY be used with "Chip & PIN" credit cards. Well planned public transit will provide a less stressful and more enjoyable holiday experience.