We stayed at Cherry Hill and liked it (although that was a long time ago....maybe 11 years now). The place was clean and well-kept. What noise you'll hear is from passing traffic as opposed to loud neighbors. Given the area of the country you're in you won't avoid that. Sites were a bit on the small side but again real estate is very precious there.
Nearly everything you want to see in DC is run by either the Smithsonian (free) or National Park Service. Good value, unless you count the tax dollars spent to support it.
We used Pohick Bay Regional Park in Lorton, VA as our home base for a week of touring all the DC attractions. If you have your own transportation to the metro, no problem to get around. Worked out great for us. Large private sites. I have a previous review on this site if you do a search.