Temple Israel in Natick is a Conservative synagogue. This is where we had our wedding ceremony and all the pre-ceremony Jewish customs (the Bedeken, Tish, and Kabbalat Panim).
They provided a beautiful Chuppah. And they were able to accommodate us for everything that we needed.
The only reason that I marked it as average flexibility, is because they cannot be flexible beyond the standards of Conservative Judaism (ie, must be a kosher affair, can't be an intermarriage, etc.).
The place is beautiful - newly renovated in the last few years. The sanctuary seats over 400. The social hall can accommodate a reception for 200. I don't believe that the rabbi charges a specific amount of money - I think he leaves it up to your discretion.