A branch of the Potomac running through the rocks at Great Falls
Greater Potomac is an exceptionally affluent and densely wooded area of Montgomery County, Maryland, home to some 80,000 people, among them many of the wealthy and powerful of the nation's capital, as well as a near endless quantity of doctors!
The principal routes leading northwest into Potomac from D.C. are River Rd and the Clara Barton Pkwy (which runs parallel to the smaller MacArthur Blvd). From Bethesda, take either River Rd or Democracy Blvd (from Old Georgetown Rd). From Rockville, the main route is MD-189 Great Falls Rd. From Virginia, bridges across the Potomac River are very few—you will almost certainly need to take the Beltway to the Clara Barton Pkwy, River Rd, or Democracy Blvd exits (for Democracy Blvd, head towards I-270 instead of continuing on I-495 at the split).
Potomac is not very public transport friendly, but there are a couple bus routes worth noting. The T2 Metrobus runs every half hour throughout the day along River Rd and Falls Rd between the Friendship Heights and Rockville Metro stations. Ride on Bus #29 goes from the Bethesda and Friendship Heights Metro stations to Glen Echo Park (see below).
Clara Barton National Historic Site, 5801 Oxford Rd (Walking distance from Glen Echo Park), ☎ +1 301 320-1410, . 10AM-4PM daily, tours on the hour. See where Clara Barton, founder of the American Red Cross, lived the last 15 years of her life.Free. edit
Great Falls, 11710 MacArthur Blvd, ☎ +1 301 767-3714, . Visitor center: 9AM-4:30PM daily. The most dramatic section of the C&O Canal National Park on the Potomac River is at Great Falls, a series of cascading falls dropping 76 feet over two-thirds of a mile. A footbridge leads out from the canal trail to an island in the middle of the river, where you'll learn to appreciate why it was necessary to build a canal instead of simply navigating the river! This is a fantastic place for a hike or picnic. The visitor center is in a hotel dating from 1831, which served nineteenth century admirers of these same vistas. During the warm months, W-Su, you can take a ride through the locks of the canal from the tavern on a historic mule-pulled boat! The ride costs $5/person, and be sure to call ahead to make sure it is in operation on the day of your visit.$5/vehicle for 3-day entrance pass. edit
Glen Echo is a remarkable little town created out of an antique turn of the twentieth century amusement park! The small suburban park  was in operation until 1960, and subsequently salvaged by the National Park Service in 1971, looking to turn it into an arts and educational center. The park itself is open... free, although activities often charge very reasonable fees.
Concerts, art exhibits, dramatic performances, puppet shows, ballroom dancing in the historic Spanish Ballroom, and a whole host of educational programs (mostly related to the arts) are in full force throughout the summer, when you can also avail yourself of the still-operating, 1921 antique carousel ($1). Check the park's website for event dates and available classes.
For the benefit of the hungry summer visitors (since there isn't anything else nearby), the Spanish Ballroom Cafe is open from the beginning of March through the end of October.
To get here by car, take the Clara Barton/Cabin John Pkwy exit west from the Beltway. Go 2.5 miles and take the MacArthur Blvd/Glen Echo exit (this is a left exit). Turn left onto MacArthur Blvd. For the park, go two blocks to Oxford Rd (just past the Glen Echo shopping center) and turn left into the parking lot. It's easy to arrive by public transport as well—the #29 Ride on Bus runs a route every half hour between the Bethesda and Friendship Heights metro stations, with a stop in Glen Echo, running roughly every half hour M-Sa. On sundays, the bus runs only between Friendship Heights Metro and Glen Echo, with no stop in Bethesda.
Normandie Farm Restaurant, 10710 Falls Rd, ☎ +1 301 983-8838, . Tu-Sa 11:30AM-2PM,5:30PM-10PM, Su 11AM-2PM,5PM-9PM; dancing F-Sa 7PM-11PM. An upscale French restaurant, which, oddly enough, specializes in simple, scrumptious popovers! It is a large restaurant in an odd spot among Potomac's suburban mansions, with a French countryside styled interior. While a fine choice for dinner (especially given the excellent wine selection), the Sunday brunch buffet ($28) and afternoon teas ($20) are extremely popular, and generally require reservations. The restaurant is often booked for banquets and events, so it is good to call in advance anyway. Afternoon tea every first and third Wednesday of the month. Full bar.$22-45. edit
Renato Restaurant, 10120 River Rd (Potomac Place Shopping Center), ☎ +1 301 365-1900. M-F noon-2PM,5:30PM-9:30PM, Sa-Su 5:30PM-9:30PM. Unpretentious strip-mall Italian dining at its best. The prices are deceptively low for the quality of food, with lunch being a real bargain. Specializes in fresh fish, although most all the appetizers as well as the pizza remain local favorites. Patio seating. Make reservations.$15-30. edit
Dolce Bolger Center, 9600 Newbridge Dr, ☎ +1 301 983-7000, . A very large three building hotel and event/conference center on a quiet, park-like 23 acres with walking/running trails. The catered food draws more or less universal rave reviews from visitors, so bring an appetite, and expect to gain weight. Be forewarned that the rooms, while nice, are quite small and that there isn't much of anything nearby—this hotel caters to business conferences, weddings, etc., rather than to casual travelers.$80-150. edit
This is a usable article. It has information for getting in as well as some complete entries for restaurants and hotels. An adventurous person could use this article, but please plunge forward and help it grow!