Herein a visitors' guide. I will be updating it daily. Please post any issues you want addressed or researched.
I am told (but did not check) that hotels are very full. If one stays at interstate hotels (try those along the Richmond Highway in Alexandria or Fairfax County) you can get a room for $40-80 a night. But you will be dependent on driving into DC, not using a subway or bus, as you will be beyond the public transit system's reach.
So this is mainly a list of free, cheap, good, bad, and safe or unsafe things.
Free
One can get free wifi access in many parts of DC: any Starbucks (and often any restaurant adjacent to Starbucks); most Barnes & Noble bookstores (which usually contain a Starbucks); Caribou Coffee (another chain, though it restricts your access to "adult" sites including some FaceBook functions); Illy's (at New Hampshire Avenue and M Streets NW), which also has the best coffee.
Cheap
Silver Diner
3200 Wilson Bouelvard
Arlington, VA
and other locations see:
www.silverdiner.com
[Clarendon metro stop, Blue and Orange line)
Pete's Diner
212 2nd Street SE
Washington, DC
(Good reasonably priced food on Capitol Hill; eat with the Congresscritters' staffers; across a side street from the Library of Congress)
[Capitol South metro, Blue and Orange Line]
Tandoori Time
1140 19th Street NW
Washington DC
Lunch buffet all you can eat (Indian) $7.99 plus tax
(downtown business distict)
[Dupont Circle metro, Red Line]
Pasha Bistro
1523 17th Street NW
Washington DC
tasty hamburgers and middle eastern food; free wifi; indoor & outdoor seating
(Dupont Circle, gay area)
[Dupont Circle metro, Red line]
CVS is the DC area drugstore chain and most carry simply hardwares and basic groceries (milk, bread, canned soup, TV dinners)
Trader Joe's
1101 25th Street NW
(25th and L)
Washington DC
Competitively priced food and wine, underground parking garage free to customers, free sample counter in back cooking up a different treat every day
[Foggy Bottom metro, Blue and Orange line]
Good
Libertarianish Virginia economics professor Tyler Cowen extensively explores and reviews restaurants, especially Northern Virginia Asian fare, at
Tyler Cowen's Ethnic Dining Guide - All food is ethnic food.
Adding my own "bests"
Westend Bistro
1190 22nd Street NW
Washington DC 20037
Westend Bistro | by Eric Ripert
DC outpost of Manhattan restauraunteur Eric Ripert. Slightly pricey but the complicated market salad or the spaghetti bolognese can be enjoyed for under $20. Nancy Pelosi, Alan Greenspan, Andrea Mitchell, Clint Eastwood, and other notables, good and evil, local and visiting, may be spotted.
[Dupont Circle metro, Red line, or Foggy Bottom metro, Blue and Orange lines]
Willow
4301 North Fairfax Drive
Arlington, VA
Willow Restaurant - Arlington Virginia
Happy hour prices much cheaper than many DC area restaurants. $5 glasses of very good wines and $5 appetizer plates. The quality of the food is similar to posh downtown DC see-and-be-seen places that cost 2-3 times as much. Outdoor and indoor seating.
[Ballston metro, Blue and Orange line]
Jaleo
480 7th Street NW
Washington DC
Jaleo — the renowned Spanish tapas restaurant of José Andrés
Really near the Mall and monuments and close to a variety of metro stops. Tapas/Spanish.
[Chinatown metro, Red line]
Safety and Mores
DC's population includes refugees from every country, as the families of embassy staffs of third world countries tend to stay in DC whenever a revolution in their homeland means that anyone in their family would be in danger if they went back. Most taxi drivers and many waiters/waitresses (especially in local coffee shops like the Bread and Chocolate chain) are immigrants, frequently from east Africa or Arab countries. As a rule, African immigrants do not like for you to assume they are African Americans and especially do not like for you to guess they are from a neighboring country (e.g. Eritrea, Ethiopia, Somalia) with whom they may have political or military tensions. It's rare to meet anyone who gets really offended, but you can still be aware of the issue.
Many parts of DC are safe beyond the areas I will list here, but why chance it if you don't know where you are?
If you are on the subway stay on the Red line between Union Station and Shady Grove, Maryland. If you are on the Blue or Orange line do not go past Eastern Market (Capitol Hill) toward the Potomac Avenue stop and beyond; stay in NW DC and points in Virginia. Do not use the Green line or the Yellow line. These rules are even more important at night. There is of course nothing wrong with many other areas; but you don't know where you are, so you should not explore them.
If on foot or in a cab or bus, stay in Bethesda, Arlington (preferably north Arlington), Crystal City, Falls Church, Annandale, or Alexandria, or in DC only in northwest DC west (i.e. larger street numbers) of 14th or 16th streets, or if on Capitol Hill only in SE Capitol Hill (zip 20003) between 1st and 8th Streets, not farther out than 8th (e.g. 9th, 10th etc). (Or stay on the Mall and at the various monuments.) Again there are many other lovely places, from the Catholic University of America to Silver Spring, Maryland. But you don't know where you are so you cannot go, especially at night, unless you take me with you.
Bad
Nancy Pelosi's condo
Washington Harbour
3030 K Street NW
Washington DC 20007
(30th and K Streets NW)
Harry Reid's condo
Ritz-Carlton
1155 23rd Street NW
Washington DC 20037
(23rd and M Streets NW)
Bob Bauer/Anita Dunn
4413 Stanford Street
Chevy Chase, MD 20815
Tom Daschle's house
2830 Foxhall Road NW
Washington DC 20007
(Feel free to protest!)