Hi friends, I want to take a day tour visiting among others White House, Capitol Hill , Air & Sea Museum etc on a Saturday. I will be starting from China Town and I have about 5 hrs (including lunch break) from 12.00 to 5.00 PM. I will appreciate to know which bus or train should I take to visit those places and other DC attractions within the above time span. I am looking for an inexpensive way of visiting the city so I am not taking any guided tours.
Thanks for your suggestions.

Bro you have only 5 hours and do not think you will be able to do much more things.
Take a bus to  DC, stop closer to WhiteHouse, walk around and most of the visting things are in walking distance, bundle up as you are walking.
Still; 5 hours time and you wanted to utilze it, sounds good plan.

 Basically there is nothing much to see in DC. Just walk from Capitol hill all the way to Lincoln Memorial, you will see DC on the way and thats it. That will take about 2 hours.

 Take a Circulator Bus, get one day pass www.dccirculator.com/ look for route and stuff here!!

Don't forget Narural History Museum and Lincoln Memorial/WWII/Viertnam/Korea War monuments!!

+If you starting from ChinaTown everything is walking distance if you are an average walker :-)) and can finish in 5 hrs!! (museums you can just walk by can't spend time though)!!

Thanks for your feedbacks Alterego, Syanjali and Lahure Kanchha.

Washington DC is a wonderful place to visit, but 5 hours is far too little.

Here's what I would do:

Start at the US Capitol, walk through Air & Space museum quickly (well I like science, that's why I chose this museum, but you may choose any other Smithsonians), make your way to the White House (you can gaze from outside), cross over to Jefferson Memorial via the Monument and WWII Memorial, visit Holocaust museum (it is quite something, I tell ya), walk by the reflecting pool while thinking of Dr. King's "I have a Dream" speech, Korean War Memorial, Lincoln Memorial, then Vietnam Memorial.

By now your 5 hours should be up and you probably would be thoroughly pooped with all that walking.  If not, you can move on to Georgetown area and enjoy some fine dining/shopping.

Thanks Riten