Hello Time Traveler (and Pat),
I've traveled with GoAhead twice (walking tours of Tuscany and Provence) and am currently booked for trip #3. I have had excellent experiences: great guides, wonderful food, beautiful sights, and can't wait to see the Amalfi Coast in June.
The beauty of having only half your meals included is finding places on your own to try. Your guides will help, but if you check which days don't have dinners included and hit the internet with a few searches, you'll find some amazing places in these lovely towns.
May should be a good time to travel. I always go in June. While in Tuscany in 2007, one drop of rain hit my head while in Assisi: in Provence, we had some rain driving into Nice, but we were on the coach so it didn't matter.
Italy is an amazing country and GoAhead will serve it to you on a lovely platter.
Enjoy!
Ed