We will be in DC for a full week with two 12 year olds. Plan to cover all the major sights. Will have a car so could venture outside DC. I haven't been in 15 years, any suggestions?

A full week in D.C. with teenagers is probably too long. They probably aren't quite at the age where they will really "appreciate" the monuments, museums, etc. I live here and have seen too many very unhappy teens trudging along the Mall, arguing with mom and dad about not wanting to go to another museum! A couple of brief museum visits (Air / Space and American History are usually hits with the younger set), a look-see at the Capitol and the White House, and a trip to the top of the Washington Monument are probably all they'll be up for. A couple of "fun" tours might be the Bureau of Printing and Engraving where they can see first hand how money is printed or the tour of the FBI with target shooting demonstrations and lots of cloak and dagger stuff. Union Station is also fun for younger kids. Has been renovated to include a spiffy food court, shops, etc. The restaurant "America" in Union Station has a huge menu and is a lot of fun for a family. The Zoo is always a nice visit if they're into animals, etc. Baltimore, about an hour north on I-95, has much more to offer for kids, I think. The harbor is great. The Aquarium and the Maryland Science Center are fun, kid-oriented attractions. If the Orioles are in town, a game at Camden Yards would probably be a big hit. If you've got spare time, the 3-hour trip to Williamsburg is well worth it. Tour the restored colonial village and then spend some time on the rides at Busch Gardens Theme Park. One of the classiest amusement parks I've visited. Have fun!

I agree with much of what Sammy has to say.
I would add that you need to arrange for the ticketing for the Bureau of Engraving, the White House and the FBI in advance. The Park Service used to have a ticket booth near the White House for tour tickets to 1600 Pennsylvania Avenue. I'm not sure, but I think it's still there.

I've spent lots of time standing in line for Engraving and the FBI. I don't recall the reservation system for those tickets, but it's worth checking into.

Also, we took our daughter (7 at the time) to Ford's Theater. She still talks about it 4 years later.

Sammy offers excellent advice; a week in DC is probably three or four days too long for kids of that age. As you're mobile, however, here are four suggestions for things outside of the immediate area that might hold the attention of a couple of 12 year olds so as to stretch your stay out to a week: 1) the C&O canal towpath, a national park located near Potomac, MD. You can ride an authentic, mule-pulled barge down a swatch of the old Cheasapeake & Ohio canal. You can also see the Potomac at Great Falls, a series of rapids where the river is wide and rocky. 2) the Manassas National Battlefield in Manassas, VA. The site is well-interpreted and easy to follow. There are numerous guides to better explain what you're seeing. 3) Oriole Park at Camden Yards is one of the best ball parks in the country. It is a 45 minute drive from the center of DC. If interested, call today, as the games draw very well (especialy with the Birds in first place). 4) Sammy mentioned Williamsburg and Busch Gardens. I'd ordinarily agree, but having been in Norfolk this weekend, I can report that I-64 is under construction, and the traffic jams around Williamsburg were monstrous. Several steps down the amusement park quality scale, but much closer to DC is Kings Dominion, near Ashland, VA; roughly 70 miles south of DC on I-95. It is a reasonable day trip while Busch Gardens would almost certainly have to be an overnight one.

The Ford's Theater suggestion is excellent. I can't believe I left it off my list. A couple years back, I took my 14 year old sister there. Though she was completely blase about the rest of her Washington trip, we had to drag her away from the theater and the adjoining museum which documents the events leading up to Lincoln's assasaination. Maybe it's the macbre element or something, but for some reason kids do seem to connect with the site of Lincoln's murder. My sister, too, still talks about Ford's Theater two years later!

Kings Dominion has lots of coasters but be sure your kids are 54" or taller or your money will be wasted. The Holocaust Museum is a must-see but only if your kids are MATURE. Very sombering.

The Holocaust Museum is a must for people of all ages, but especially young people. I was there with my 7 & 8 year grandchildren last April. They were moved and asked many questions. The Museum shows how millions of lives were distroyed because of the teachings of a evil man, Hitler. Educating young people will prevent it from happening again.

Yes to FBI, C&O footpath, Williamsburg, Aerospace Museum, Ford Theatre, but how about a boat trip down the Potomac to Mt. Vernon? Fun little ethnic restaurant in Georgetown? I don't think a week is too long--you can let them sleep in some mornings and not push them. We've traveled a lot with our kids and found that the look so grumpy and out of sorts because they're tired and haven't had enough pizza, hamburgers and soda and because they've had to get up early to be with Mom and Dad. Give them time to go to a movie or find the local Hard Rock Cafe!! I think it'll be fun and relaxing for all! There's also Georgetown University, if they might like a look at the campus and the chance to buy sweatshirts etc. Enjoy