We will be in Siena and would like to visit a quaint village for lunch and to get away from the crowds. Any suggestions, I realize this is peak season
Also are there any favorite beach town, Forte di Marmi, Via Reggio...

A tiny, walled village is Monteriggioni. You can visit the whole village in less than half an hour. Il Pozzo is said to be a good restaurant that does Tuscan (i.e., plain) cooking well. Unfortunately, I was there mid-afternoon and had to settle for a gelato from one of the bars.

Il Pozzo has a Web site:

http://www.ilpozzo.net/

It might be wise to reserve, particularly if it's for Sunday lunch.

Il Pozzo is good, but not inexpensive, and you should definitely reserve if you want to get a table. It's quite popular.

There are many quaint villages within an hour's drive of Siena, but if we've heard of them, they are likely to have crowds. Quite near to Monterrigioni (on the other side of the autostrada) is Colle di Val d'Elsa. The upper part of town is quite charming to wander in and doesn't get the crowds you find in Pienza or Montalcino. Sorry, I can't recommend a restaurant there.

You could just be adventurous and wander some back roads until you see a village that looks interesting. Any small, family-owned restaurant with Mama in the kitchen is more likely than not to provide a delicious meal.

Colle Val d'Elsa is tiny and charming. There isn't much to see other than strolling the tiniest of towns. If you decide to eat there, I recently ate at Ll'oste di Borgo, which was a family run tiny restaurant that had only a handful (less than 10) tables. We had the pasta of the day and bruschetta, which was just heavenly. Enjoy!