Baltimore is nice to visit. Check out this website for kids activities there. The aquarium is fabulous.
http://www.kidslovedowntownbaltimore.com

No need to rent a car. The Amtrak adult fare from WAS to BAL is $11.
2 adults and 2 children on the Northeast Regional will be $33.
In addition to the aquarium you can see the USS Constellation which is a sister ship to Old Ironsides.
On the left side of the Amtrak homepage, you can see deals on hotels including 1 within walking distance of the inner harbor for less than $200 for Sunday night.
The fare back from Baltimore to the BWI station is only $5/person. There are several BWI hotels but not too much to see in that area.

I agree -- stay near the airport or in Baltimore inner harbor and take the train -- Amtrak or the light rail. Aquarium, museums, nice walking-around area ... maybe try to catch an Orioles game.

I'm not clear on what you are asking when you want a community to venture to. Do you mean a place to stay or just to visit during the day? I agree with train idea and that Baltimore is the most interesting place around there. I'm in that area a lot and frankly, there's nothing really of interest in it.

I suppose if I had to name some place that is sort of quaint, it might be Ellicott City but that is really stretching it, if you mean a place to spend all day. Columbia is a nice place to live, but there isn't really any special point of interest there but a mall. There is Goddard Space Center but I don't know if they have any tour for visitors or not.

I don't know if they have hotels in Ellicott city, though, if you are looking for a hotel. I'm sure they must in Columbia, and there is Catonsville, also. Catonsville and Ellicott city aren't that far from BWI, Columbia is farther. There are plenty of airport hotels, though. If you were going to stay in some hotel, those places would be easier than Baltimore (and probably cheaper).

The area right around BWI is just suburban (where I grew up) but BWI is a pretty easy ride from downtown Baltimore. I stayed at the Hampton Inn downtown that was right near the light rail, strolling distance to all the inner harbor attractions, right near Camden Yards and had baseball theme decor in the lobby (subtle but fun). It was the nicest Hampton Inn I've stayed in and not too pricey. From there you can take a taxi to Penn Station for about 12 bucks then the local train down to the airport for maybe 6 bucks (I'm not totally sure of the prices but not overly expensive at all.)

Baltimore has lots to offer kids. The aquarium is a blast and so is the science museum. I just went back for a visit and loved Miss Shirley's for brunch right near the harbor and found the new McCormick spice store in HarborPlace to be lots of fun (the McCormick factory was right there downtown when I was a kid and you could smell different spices depending on what they were making each day).

Too bad we miss the Twins play the Orioles by a week. That would have been a blast. The Orioles are in ny when we're near. Maybe The Nationals, but I don't know where we'd leave luggage as we'd be inbetween hotels and game time is Tbd.

Are there historical sights in Baltimore? Is Gettysburg worth the trek?

With the short time you have unless you have abusing desire to c Gettysburg, I would not take the time to visit it.
Perhaps your hotel would keep your luggage if you decide to go to a Nationals game.

Hi googs,

Baltimore's a great choice,as the others have mentioned. And having being around since the early 1700s, Baltimore is pretty rich in history to boot, at least on a USA time scale. Baltimore made some moderately successful efforts to preserve its history when other places were razing buildings in the name of development.

Mount Vernon, where the terrific Walters Art Gallery is located across from the Peabody Institute, is a beautiful historic neighbourhood. Mount Vernon Square was the center of Baltimore public life in the early 1900s.

Taking the water taxi is a fun activity while in Baltimore on a nice day, and gives you access to some interesting historic sights in US history. Accessible by water taxi from the Inner Harbor, Fort McHenry is in Baltimore, where the Battle of Baltimore took place in the War of 1812, a battle which inspired the lyrics created by Francis Scott Key in "the Star Spangled Banner". Fell's Point is another charming historic neighbourhood on the water taxi line; I'm pretty sure Harriet Tubman lived there at one point and think Frederick Douglass did also, but don't quote me on that latter fact. Federal Hill is another delightful historic neighborhood, which you might enjoy checking out for its Cross Street Market, a place I'd describe as "very Baltimore". All neighborhoods I've mentioned in Baltimore are lovely for taking a stroll.

It's not as close to BWI as Baltimore, but another possibility as a base would be making a small sidestep and basing yourself in Annapolis, Maryland. Annapolis has a picturesque early 13 colonies-feeling, a walkable central core and quite a number of interesting historic sites and handsome homes to visit. The harbor is in my mind more aesthetically pleasing than Baltimore's. Annapolis would not be a bad choice if you prefer something smaller after DC.

Best wishes, Daniel

Thank you Daniel! Annapolis sounds like a low-car-stress type of place and a happy in-between spot from DC to BWI. The neighborhoods you describe in Baltimore are just what I was looking for.

Is the Bromo-Seltzer tower or Holocaust Memorial work a look?

Thanks for the Miss Shirley's tip, BlueSwimmer.

The Baltimore (BAL) Amtrak station has baggage storage.
You can leave luggage there until your trip back to the BWI station. There is public transit from the station to the Inner Harbor. You can take a water taxi to Fort McHenry for the history lesson.
On the Amtrak website you can find hotels near many of the major stations. Some of the hotels give a discount to Amtrak customers.

I'd take a cab from the hotel in Baltimore to BWI - the Amtrak (or MARC) to BWI is a hassle. The train station is a 10 to 15-minute bus ride from the terminals. The bus shuttle is free, but the dragging around is easily worth a $20 avoidance fee (the difference between the cab and the train).

Sicne you seem interested in Baseball, note that Babe Ruth's house is in Baltimore and you can visit it.

ALso, there is a nice wildlife refure right off of BW Parkway on way from D.C. to BWI. NAtional Wildlife Visitors Center refuge. Nice to visit, museum is good, lots of open land and animal habitats for walking on their grounds. I used to take my kids there, we loved it.

http://www.fws.gov/northeast/patuxent/vcdefault.html