Best time to visit N.Italy is May-July and Spetember-October. Ferragosto is heaving with Italians at the coast/lakes and all the cities are shut up.
Go to Lago di Como/d'Iseo or the Ligurian Riviera to relax. I think Milano is a dump personally. Torino, Verona, Vicenza, Bergamo,Bassano del Grappa, Trento are nice.
Modena and Bolgna are good if you want a car interest holiday.
Further South Lucca is gorgeous, Firenze is nice but packed and sweaty.
Re wines, I import from my relatives in Chianti but they don't make enough to export generally.
Best wine areas are Trentino, Friuli, Piemonte, Toscana/Umbria, best go yourself, see what you like and strike a deal. The good stuff isn't cheap though.