If you want to see something in Wheaton, this should be first on your list. This beautiful place has a wide variety of plants from all over. Its Conservatory houses a range of tropical plants, and the formal outdoor gardens are very attractive. The Rose Garden, Gude Garden, Yew Garden, Perennial Garden, Aquatic Garden, and others offer a fine array of flowers and foliage. Of particular interest is the new Reflection Terrace, dedicated to the innocent victims of the infamous snipers John Muhammed and Lee Boyd Malvo.
Brookside Gardens has a nice gift shop and information desk. It's become a favorite spot for weddings.
My visit was too late in the year for some of the activities here. But it's still a nice place for a short day outing. If you want to get outside the city and hike around, or just enjoy some nice greenery, then here's a good place.
Wheaton Regional Park has a few miles of hiking trails, playgrounds, picnic areas, an old carousel, a miniature narrow-gauge train, an ice skating rink, a dog pen, and best of all Brookside Gardens (a separate tip). It's a perfect place for families, and only a short drive from the Beltway.