Parking in Washington DC

Summers in the tourist parts of DC are very crowded, and the week of July 4th is pretty much the peak of the tourist season. I would advise against driving to the National Mall area; there's little parking in that part of town anyhow. Also, DC is not particularly driver-friendly if you're not used to it.

Driving to Friendship Heights or Tenlytown isn't going to save you much in terms of time or money - there are only commercial parking lots nearby, not like the big commuter lots in the suburbs, and in the time it takes to drive there, you'll be almost downtown anyhow.

One option to consider would be to take Metrobus. There are buses that use the MacArthur Blvd, Mass. Ave, and River Road corridors; most of them feed into the Friendship Heights station, but the D5 goes all the way downtown from MacArthur Blvd. The bus is a little more complicated if you're not used to taking them, it's but reasonably quick (unless you're traveling during rush hour, which I'd also discourage), and there is pretty frequent service. The buses are clean and safe, particularly in the part of town you'll be in.

There are also single-day and multi-day passes that are available, and are accepted on both Metrobus and Metrorail. You can take the bus into town, and travel around in town via the subway. As @choster mentioned in his comment, Metro has fallen on hard times lately, so you may end up on a bus on the weekend anyhow :-(

Another plus is that the D5 bus travels through Georgetown, where you said you're interested in spending some time as well.

Metro's route planner at https://www.wmata.com/ may be useful.

All good answers. Given that this is my every day commute, and that you'd be visiting on weekdays, I'd recommend driving into the city from Brookmont via Canal Road. During the weekday mornings (6-10), Canal Road is one-way entering into the city, and in the evenings (3-7) its the other way exiting out of the city. This will work in your favor, both ways.

As you are visiting the National Mall area, consider parking at the Portals garage on 1250 Maryland Ave SW. It's a short 2 block walk to the mall and also walkable to the Monument and the Capitol on a good day. They have an early bird rate of $13 per day if you get in before 8 AM; $21 after that, if available - there are other garages too, and as mentioned in the other answers, it'll be cheaper than riding the train for 4 of you. If you are spending the entire day, be wary of street parking - which is usually allowed only for a max. of 2/3 hours - they are strictly enforced.

Enjoy DC!

I'm a DC native who has moved, and I'm going back to visit family exactly then. And a lot of other people, too. July 4 is a very crowded time there.

The Bethesda Metro station has a dedicated parking lot (for $); Friendship Heights does not. If you are responsible for getting to the Metro, keep that in mind.

Alternatively, Clara Barton Parkway to Canal Road is a quick (30-40 minutes) driving route to downtown from Brookmont. For the Smithsonian, continue on the Whitehurst Freeway, I-66, and Independence Avenue. Parking will be difficult. I would be prepared to pay for a commercial garage.

In addition to Andrew's answer, I have previously parked at the Fashion Center at Pentagon City. This is a shopping mall that connects directly with the Pentagon City metro station.