New York City
New York City is the most populated city in all of America with around 8.8 million people there. New York City has pretty much anything you might ever want to do there. From museums, monuments, fun attractions, and beautiful sights, the options are endless.
Some cool things to see here are the Empire State Building, Times Square, Central Park, the Statue of Liberty, the National 9/11 Memorial, and the One World Trade Center. This is also home to Grand Central Station and the Yankee stadium.
Like D.C. there is a subway, but an even better option, and most likely quicker, would be to bike around the city and see all the sights as you go.