I know that there is a metro stop near the Sheraton, but I am not certain how difficult it is to walk to from the Sheraton. Sidewalks, crossings etc.
My desire is to use only the metro and my feet, no cabs. In the past I have done a lot in DC without using cabs. My wife recently lost her job and my business is down significantly, so coming to DC is a financial sacrifice.
I will call the hotel and if they will give me details on that I will post that info.
The Sheraton is at a Metro stop about 1 block away. They will be running shuttle buses for us to get to and from The Mall and Walter Reed.
Southwest will not appear in searches on some travel sites - you must go directly to their site. Jet Blue and Air Tran also service BWI. If you are checking a travel website for air transportation, use the city code WAS - this causes the search engine to look at all three DC area airports (Reagan National, Dulles, and BWI) so you can see your cheapest option.
Sometimes taking Southwest to BWI can save you hundreds over the other airports (though sometimes not). But worth checking if you've willing to accept less rapid connections to save on your airfare.
Beware of DC cabs - last I was in DC they were not metered - they operate on a Byzantine “zone” system that is an open invitation for drivers to relieve you of excess cash.