When you're looking for picturesque or meaningful sites for your wedding, don't forget to check out the historic or cultural buildings in your area. Some of these venues offer great rental discounts and have quaint, impressive or unexpected features that make dynamic photo opportunities, like elaborate entrances or stained-glass windows. If you think all that marble or stone looks too cold, consider it a great neutral background for loads of flowers -- and your wedding party, of course.
To make sure you've covered all the bases, check with your local chamber of commerce for suggestions. Sometimes college buildings and state owned buildings that you wouldn't consider rentable are available for weddings on a limited basis.