I recently purchased the Moon Handbook Washington, 8th edition.
Previously I have used the 6th edition by Don Pitcher. Even though the older edition is outdated regarding lodging, restaurants, etc, I found it to me much more helpful and better organized.
Specifically, I appreciated all the local area maps in the older edition (112), versus only 44 maps in the 8th edition. Also, the index in the older edition was much handier, with the separate boxes for individual topics such as fairs, ferry service, hiking and lighthouses.