Wow.... Guys, we just returned from 5 days in DC...First thing I'd like to say is thanks you for all the responces and ideas.. As you most likely know, it rained for about 48hrs straight(Monday and Tuesday).. We saw 11" of rain in a 24hr period which flooded downtown DC and the surrounding areas.. The National Archives building reported 10' of water in the basement and was the only thing we planned on that we couldnt see..
We started off Saturday morning(late, after arrival and check in at the hotel) by going to Arlington.. That alone was worth the trip.. We saw a good bit of it, including the changing of the gaurds(impressive).. We were still getting our bearrings and didnt do the Tourmobile because of the late start and doubting we'd get to the monuments so we did miss a few things like the Rober E. Lee house and a couple of other monuments and headstones, mainly because we didnt know how much was there.. One could easily spend a whole day there, just be prepared that they dont sell water(or drinks) there and the fountains are few and far between .. That was a good suggestion to start with the Tourmobile with the monuments, though we did that Wed and it worked out good, shoulda followed that suggestion and saved Arlington for later allowing more time though..
Sunday, we did the Museum of Natural History and of American History... UNBELEIVABLE

....Good thing we went because they were the best museums we saw there and closed due to the rains on Monday..Incredible amount of history there including the original flag the Star Spangled Banner was written about, very powerful display and history behind it.. And the displays of the wars we have been involved in, WOW......
Monday, we did the Air and Space Museum at the Dulles Airport(
Udvar Hazy) wich was kinda tough to get to.... The Metro doesnt go there and allot of people werent aware it existed.. I recomend that one over the one in downtown, though there is a buss between the two.. I recommend a cab(directly) to the Udvar Hazy for the 10am opening, see it all then take their bus downtown to get a start there(the Metro will get you back to the hotel from there).. I found, for us, that we couldnt do more than two museums in a day.. Each museum(all of them) took at least 3hrs to really see, if you are really into certain things an read everything, it would take longer...
Tuesday(still raining) we went back to the Air and Space downtown and finished it, pretty good, though I prefered the other one.. We finished up around noon and began walking(GOOD GOD what alot of walking) between the raindrops, ducking into cover whenever we needed to... We walked down to the National Aquarium, most dissapointing part of the drip, even worse than the rain... I've seen better displays in pet shops, it was a terrible waste of time and money.....We then walked around the corner to the White House visitor center then in front of the White House for some photo opps.. Then, taking F street down to 10th, we found the Fords Theater closed so dropped into the Hard Rock for an early dinner... The Spy Museum was interesting... It was a little different than most, more interactive activities and displays.. My son loved it...
Wednesday we decided to do the Tourmobile arround town seeing and hearing about the sights, the Capitol, Washington, Thomas Jefferson, Lincoln, Korea, Viet Nam, WWII memorials and even got to see the choppers coming to pick up the President.. That was pretty cool, seeing the choppers come in with decoys and security, including snipers on the roof... We ended the day at Union Station.. That was verry impressive in itself... The shear size of the bulding and craftsmanship was incredible... We then headed back for check out and back to the airport..
So, again, thanks for the advise.. It was a very rewarding vacation, we all enjoyed ourselves and wont soon forget it.. May have to make a weekend trip back to see the Archives, Fords Theater, Printing and Engraving and the Naval Museum, White House and Capitol(last three requiring advanced clearance and reservations)..
My recomendations allong with the above are to make sure you stay within walking distance of the Metro.. We stayed in Tysons Corner, not a bad thing, but the hotel shuttle limited us a bit.. Look at the Metro map before choosing a hotel, plan the trip around that.. I'll add my recomendation(as the many before) to wear comfortable shoes and bring water...Awsome vacation, though I would also recomend that you would wait until the children are old enough to appreciate it first.. We saw alot of young kids there(newborn-6) that just wanted to play and really had no clue what they were seeing, but to ewach his own I guess... If anyone has a question, let me know, I learned allot about that town.....

BTW, i'll have some picture coming later....