Sandy Point State Park is a nice family beach destination close to the DC area. It is located on the Chesapeake Bay at the last exit before the Bay Bridge. From the beach area you can get a nice view of the bridge as it stretches all the way across the bay. Just north of the bridge you can see the Sandy Point Lighthouse which was built in 1883.
In addition to the beaches, Sandy Point has many picnic areas, fishing piers and jetties, a marina, and a new visitor center with specimens of local wildlife. You can also glimpse wildlife from the leisurely hiking trails that take you into the marshy areas and pine forest next to the beach. I was lucky enough to see a Peregrine falcon flying overhead when I visited the park.
On summer days you will need to come early because parking fills quickly. During April until October there is a fee of $5 per person for MD residents to enter the park. See the Sandy Point State Park website for more information about hours and fees.