Although winter is right around the corner and outdoor weddings are not the best choice... it is a good idea to set dates for 2011 spring, summer and fall weddings (or 2012). There are so many national and city parks in every state! These parks are gorgeous for ceremonies and even can have a reception space. In DC there are some great places where you can see the sites and still have a beautiful park view! Depending on you location the park may be free or very cheap to rent out for the ceremony and/or reception. Although there are some parks that may not be suitable for a wedding, some parks are perfect.
Of course everyone knows about central park in NYC, but it is truly beautiful and has many great places for a wedding ceremony! Central park does run some fees for using it, but if you live in NY or Jersey this may be the perfect choice for your wedding. In Washington, DC you have the National Mall, Constitution Gardens, George Washington Memorial, and other memorial parks (http://www.nps.gov/nacc). This places are also amazing for engagement photos! Also... a wedding on the tidal basin near the Jefferson memorial in late March or early April would be amazing with the cherry blossoms! When you think of parks you may not think of the beach, but there are some great beaches that are covered by the National Parks or may just be a public beach. Like I have said a million times it is always important to look into all your venue options, you may just be surprised at what you find!
There are so many options around your area so look at different parks and memorial parks. There are also some great national houses and places that are frequently used for weddings! I love the idea of having more than one engagement picture shoot. In DC why not go to the memorials, a park, and a local location you love? With a good planner and vision you can make any place a beautiful wedding location.