Chicago, on Lake Michigan, with nick name The Windy City, is one of the largest US cities. The Sears Tower is one of the tallest buildings in the USA.
The Grand Canyon is really grand. When standing on the ridge of the canyon and looking 1 mile (1600m) down to the river Colorado that created all this, you do owe the river a lot of respect. It is possible to walk all the way down and back up in a day, what can be recommended.
Las Vegas is the show and gambling capital of the USA. World famous and featured in many, many movies. A wide variety of hotels from budget places to top-class resorts.
Los Angeles (aka. City of Angels) is the 2nd largest city in the USA and has a lot to offer, including great shopping (a la Pretty Woman), Hollywood, Venice Beach and sports (L.A. Lakers).
New York City has a few nick names, for example "The Big Apple", "The City That Never Sleeps" and "The Financial Capital of the World". We cannot list everything that there is to do in NYC, because it is too much. The basics however are the Statue of Liberty, Times Square, Broadway, Little Italy / China Town and the Empire State Building.