Touring america

I'm from England and was thinking of taking a gap year before going onto university next September (2010) and was planning on touring the States with my best friend for the whole year.
I know we most probably won't get the opportunity to visit every...

state/city so I'd like to know which are the best to go see.
Which have the best landmarks, night life, attractions, shopping centres etc...
You'll all have your individual opinions but I'd just like to see what you'll suggest =)
Thanks for your help =)

Here's a few of my favorite places in the the US

Niagra Falls, New York. Be sure to take a ride in the Maid of the Mist to get a close up view of the mighty falls. You should pop across the boarder to the Canadian side because some of the best views are over there.

Mackinac Island Michigan. No cars (except emergency vehicles) are allowed on this island, all transportation is by foot, bicycle, or horse. Leave your bug spray on the mainland because there are almost no insects here (a peculiarity of the island). There are tours or you can rent a horse and buggy and explore on your own.

San Antonio Texas. Visit the historic riverwalk and the Alamo. Sea World and Six Flags Fiesta Texas are fun stops. At Six Flags Fiesta Texas the Superman Krypton Coaster is my favorite roller coaster in the whole world.

Monterey California. The area here is gorgeous and you will see lots of sealife. Visit Cannery Row, the old fisherman's wharf, and the world famous Monterey Bay Aquarium.