Concur–this is a fun market and you can do very well putting together a picnic lunch here. You may be too late for the Palio but perhaps you will be able to attend the Festival delle Sagre?
Ditto this. The temple to Barbaresco.
I have been to the Produttori tasting room once and had a really interesting and pleasant visit. On another occasion they were not even open, though they were quite polite when I inquired and said apologetically that they were just too busy (or perhaps short staffed) that day to host visitors. I have also had an underwhelming experience at Gaja, where the individuals we interacted with were borderline rude. That’s always left a bad impression with me. YMMV.