We spent 3 weeks in Italy and Venice and Florence were our favorites. We did Venice, Florence, Rome, Sorrento and Day trips from Florence with 'WALKABOUT FLORENCE' to some Tuscany towns. May want to check their website out, they have a great CHIANTI WINE & FOOD SAFARI TOUR which was wonderful, as was their BEST OF TUSCANY TOUR.
It may be too late, as we booked our B&Bs 6mo in advance, but in Venice, we loved CAMPIELLO ZEN . . . we found it on TripAdvisor. It was not in the main St.Marks district, but we wanted to be off the beaten path. It was steps away from the Vaporetto, which made getting around Venice very easy. The breakfasts were fantastic and it was close to one of the best meals we had during our 3 weeks in Italy- La Zucca (they even made the RSVP for us as they book weeks out). A B&B in Venice is a great idea because the owners are so helpful with maps, directions, how to use the Vaporetto, where to buy authentic Venetian/Murano Glass beads. We also loved our boat trip to the lace island of Burano while in Venice. The Rick Steves Italy book is so helpful . . . buy it. It also gives great walks thru all the towns you are visiting.
Since you are foodies, check out 'Eating Italy' in Rome - we did 2 walk/food tours with them that were wonderful. Plus a great way to see some areas of Rome you'd miss. Don't miss the Pantheon, Colosseum Forum, Vatican.
Florence has some amazing restaurants, but don't miss the famous Sandwich places are that listed in TripAdvisor . . . they happen to be in the top 10 best ranked - I'm not even a sandwich fan, and the breads and hams and salamis there are like nothing we've ever had. PM me if you need other restaurant ideas, we spent a week in Florence. We are planning to go back in Dec we loved it so much.