It's not "Little Italy." It's the North End.
Mike's Pastries is wildly overrated in my opinion. Maria's is much, much better and less of a tourist trap than Mike's. As far as restaurants go, the original Regina on Thatcher is good, as is Ernesto's Pizza on Salem Street (though Ernesto's is more suitable for grabbing a quick bite for lunch). Antico Forno (also on Salem Street) is good too. I <3 their gnocchi.
If you like beer, you could do the Harpoon tasting in addition to the Sam tour. IMHO, the Sam tour is much better, but Harpoon makes some tasty brews too. I'd also try out Boston Beer Works either the Fenway or North Station one also. They brew their beer on site.
The Museum of Fine Arts or the New England Sports Museum are both really fun too.
I'd also suggest going to Chinatown one late morning and having Dim Sum (It's like a Chinese Brunch) at Hei La Moon. It's on Beach Street.