First, a big thanks to everyone on Chowhound. We did a lot of research here before our trip and we found many great restaurants here (in fact, of the restaurants recommended here, no duds at all, as you'd all guess).
Anyway, without going through every restaurant of our trip, I wanted to hit the highlights:
Rome: two enotecas were great: Cavour 212 and Cul de Sac. Both were casual, good for lunch or an early evening snack. Best dinner we had in Rome was at a place called (according to the business card) Trattoria dal Cav. Gino. Phone is 06 6873434 (we needed reservations). Found it in the slow food guide - classic Roman food, casual and excellent.
Florence: We love Tuscan food! We had been to Il Cibreo before and we went again - and we weren't disappointed. Truly excellent. Maybe next time we'd try the Teatro del Salle - you get a meal (apparently buffet style, but supposedly as good as Il Cibreo itself) and a cultural event.
The other amazing restaurant in Florence was a casual place called Del Fagioli on Corso Tintori. Ribollita, Papa al Pomodoro, Bistecca Fiorentina - all the classics, all perfect.
Don't forget to stop at Vivoli on Stinche for the best gelato in Italy (get the orange-chocolate).
Venice: Not too much to say here. The food is just a letdown, especially after Florence, but it was fine, and da Alberto was the best we had.
Barcelona: I could go on and on about this place. The market is a must, as is Cal Pep (I won't bother with the details - it's all over the boards). We also had a great, elegant meal at L'Olive - I'd go back there in a second for my son's raw tuna salad with arugula.