I recommend-
Stoneys - obviously, they also have awesome strawberry shortcake. Don't think it is on the menu, but you can ask for it.
Adam's Rib - casual, reasonably priced, decent bbq, always packed with people on weekends.
Sakura - great sushi...Sushi Bob is the chef Mon-Sat and is excellent. We've moved, and still drive all the way there to eat his creations.
Frying Pan - very casual, a bit of a dive but good homemade food. I like their clam strips w/the bellies, chicken salad, and strawberry shortcake is to die for.
CD Cafe - a bit expensive, unique dishes. Delicious.
Silver Skewers (in Waldorf) - a bit of a hike from St. Leonard, but has really good kabobs. Suggest a reservation. Small place and just a little dressier than casual.
There's an Indian place in Lexington Park in San Souci plaza (?spelling). Pretty good food if you crave ethnic food.
That's all I can think of right now.