We have shot some really spectacular small weddings at the Physick House in Philadelphia. The outdoor garden / patio areas are spectacular. Since your head count is small, it mau be a great choice for you.
I second rmalfi's suggestion of the "Self Uniting License". It's great. Lots of our couples choose this option. In fact, we had one that did their entire ceremony on the grounds of the Waterworks with this approach.
In our gallery, #59 is from the Physick House.
Additionally, you may want to consider the Valley Green Inn (on the Wissahickon Trail). It makes for a great outdoor ceremony. Sample photo #99 is from the Valley Green Inn.
If you decide that you really want a "chapel feel", you can always check out the Hammorton Chapel, in Kennett Square. It's not that close to Philadelphia, but it does have some great advantages. It's very flexible, not huge in size, and puts you with reach of Longwood Gardens for pictures.
If you would like to see any of the samples, just visit:
http://www.barnyardphotography.com/Gallery.aspx
Written on Feb. 19, 2011