Here are a few things we've figured out while we've been here that weren't mentioned in our guide books (I might add to them if anything else comes up before we leave).
1. There's a ticket booth at the bottom of the path to the Washington Monument on 15th Street where you can get tickets to go up the monument. The tickets are free, but if you want one, you need to be there early - they start handing them out at 8:30, and by the time we got there at 8:00 there was already a very long line. Annoyingly, people save places for each other in the queue, so you can think you're near the front and then suddenly 10 people appear from nowhere. I'm fairly sure you need your whole party to be there when you actually pick up the tickets, though - I think they only give out one per person. Tickets are allocated to half hourly time slots throughout the day (until about 4:30, I think), and you can choose your slot. When we went back past the booth at 11:15, all the tickets for the day had already been distributed and the booth was closed.
2. There's a similar system at the Capitol if you want a guided tour, but they start distributing the tickets at 9:30, at a booth which is near the intersection of 1st Street SW with Independence Avenue. The biggest difference is that you can't choose your time - you just get whatever is the next time slot for which there are tickets still available. When we got there at about 9:45, they were handing out tickets for 12:30. We couldn't do that, as we had tickets for 12:00 for the Washington Monument, and they wouldn't give us tickets for a later time.
3. If you don't want to do the guided tour, you can go to the Rayburn House Office Building across Independence Avenue from the top end of the Capitol building, find the office of your state's representative (the security guards have a directory in which you can look up their office number) and ask for a gallery pass. That gets you into the Capitol building, where you can go into a visitors' gallery and look down on the Chamber of the House of Representatives. There is strictly no photography once you get up to the second floor, where the viewing gallery is, and you have to check in all bags and cameras at the top of the stairs. I'm not sure if non-US citizens can usually do this - I got in because I was with my nephew, who is a US citizen.
4. Absolutely no food and drink is allowed in the Capitol building, even zipped up in a bag. We had to throw away a couple of bottles of water and a handful of Granola bars on our way in. The Granola bars were picked up by the security screening, since we had forgotten we had them with us, and we had to go back outside to throw them away. There was nowhere we could leave stuff to come back for later.
5. The trip up the Washington Monument is fantastic, and it's really worth having a pair of binoculars and/or a really good zoom on your camera (we had both!). Although you get a specific time slot on your ticket, you may not get up at the specified time - you have to join another queue at the bottom of the monument, and people are let in about 10 at a time. You will be let in within half an hour of your allotted time, since they try to keep to schedule for the beginning of the next group. Once in, you can stay as long as you like (but there are no restrooms in the monument, so make sure you go before you get there).
6. The Museum of American History is closed for renovations until the summer of 2008. Some of its exhibits are on display at the Air & Space Museum, and some of the old coins are on display at the Smithsonian Castle.
7. Be prepared to do a LOT of walking. Most of the major tourist sites are a few blocks from the nearest Metro station, and it ends up being just as quick to walk from one to another as to try to find a Metro station. For this reason, a weekly Metro pass is convenient (if it works - the magnetic strip on mine became corrupted the first day we were here, and I've had to get the invariably grumpy staff to let me through the barriers on each subsequent trip) but won't necessarily save you money.
8. If you're looking for a specific name on the Vietnam Wall, there are plenty of rangers around with books where you can look up the location of the name. If you're sufficiently organised, you can do an internet search here before you go.
9. Some of the names on the wall are too high up to be able to take a rubbing. The rangers also have a step ladder, and will go up and do the rubbing for you if you tell them where the name is. When we were there, they also had special printed paper and pencils available for the rubbings - I don't know if this is always the case, or if it was just because it was Memorial Day.
10. It's really really really hard to find anywhere open that serves food after about 5:00 pm within a half mile radius of any of the tourist sites. If you do find anywhere, don't bother looking at the menu - just accept what's on offer gratefully. And don't expect any fruit or vegetables on the menu.
11. If you go to Mass at St Matthew's Cathedral, you can get Sunday brunch a few doors down at Beacon Bar & Grill on the corner of Rhode Island Avenue and 17th Street. There's an omelette bar where they make fresh omelettes to order, a waffle bar, loads of cooked food, salads, fruit salad, delicious-looking desserts (we couldn't fit any), and a constant supply of mimosa (bucks fizz), bloody mary or orange juice included in the price.
12. The stop for the basilica is Brookland-CUA. You can pretty much see the basilica from the Metro station - walk up through the Catholic University and follow your nose.