Because it's so relevant, I'll add another warning about the size of the US. Also, public transportation is not always quick or easy. Ground travel times between U.S. points of interest can quickly eat up your time.
The Grand Canyon is pretty, but it's also quite out of the way. I personally wouldn't recommend that you spend the travel time or budget it would requre for you to get there.
If you love history, you can spend FOREVER in the Smithsonian museums in Washington, D.C. (best part...they're free!) I'd seriously recommend a week in D.C. alone, unless your travel companions are the type who will eventually complain, "Another museum??!!"
You can get a lot of information about the Civil Rights struggles in D.C. museums...Memphis is fun, but considering all the other places on your agenda, you might need to save it for another trip. If you do go to Memphis, you have to do the Graceland tour. Totally cheesy, but I really did gain an appreciation for the man after going there.
Musical theater exists in L.A. too (either national touring shows or permanent shows like Wicked). I love attending tv show tapings...my favorite source for free tickets is
On Camera Audiences .
Oh, and if you pay full price at any amusement park, you are out of your mind. Discounts or coupons are always available.
I'll also add a plug for San Diego (my home town...but I'm not biased or anything!). You could easily spend a week there on attractions (Zoo, Sea World, Balboa Park museums, day trip to Mexico) and lying on the beach during the perfect summer weather.
