New York City is arguably the best city in the country for an incredible nightlife. With over thousands of bars, clubs and restaurants, you may run out of cash but will never run out of excitement in the city. Other than these, there are theaters, comedies, shows, music, events and festivals that will keep any traveler occupied during the trip. Added to these is the easy availability of public transportation even for late night ventures. 

2006 August - New York City Lights (Source: jenschapter3)

Here's more on the city:

This dazzling entertainment Mecca has more bars, clubs, and restaurants than anywhere else in the country, with an attitude to match. With constantly evolving nightlife scene and dance clubs that change names like you change underwear, there is always something new and exciting to throw yourself into in the Big Apple. Party trends may come and go, but New York is forever- or at least long enough for you to dive into the mania and come out alive.

 (Source: http://www.bakpakguide.com)

With so much to see and do, the biggest problem in New York City could be choosing the right place. The bars and clubs keep constantly changing names to keep up with the huge competition, which can be quite confusing. The best way to follow the trend is to make use of the guides provided by the city's publications such as Time Out New York, New York Magazine, New York Times and more. Click here for the best of the city for this year.

If you have more time and need a break from the entertainment, you are again left with more than you can choose from all the attractions in New York City. You could while away your time in Greenwich Village, Chinatown, Times Square or get introspective in the museums and galleries like American Museum of Natural History, Metropolitan Museum of Art, Guggenheim Museum, Museum of Modern Art and the list goes on. 

New York City (Source: aurélien.)

New York City is about 364 km away from Washington DC and you could drive to the city in about 4-5 hours. 

Philadelphia, one of the largest cities in the country, is a lively place with plenty of opportunities to keep one entertained. Night time is abuzz with various activities including events, music, food, shows and dance. Its diverse bar scene includes live music clubs, dance clubs, dive bars, sports bars and college bars. With so much of options, you are sure to have a great party time in Philly.

Philadelphia (Source: dbaron)

A snippet from Fodors:

Philadelphia has a rhythm of its own. Whether you're listening to the Philadelphia Orchestra while picnicking on the lawn at the Mann Center for the Performing Arts, or having a jazz brunch at one of the countless fab places all over town, you'll soon be caught up in that rhythm. You can listen to a chanteuse in a chic basement nightclub, dance till 2 am in a bustling bistro, or sip cocktails in any number of swank lounges.

 (Source: Nightlife & the Arts in Philadelphia | Fodor's Nightlife Reviews)

The best part of Philadelphia is that the nightlife spots are located close to each other making it convenient for club or bar hopping. The neighborhoods to enjoy the best nightlife in the city are Old City, Northern Liberties and South Philadelphia. Take a look at Greater Philadelphia Cultural Alliance and Philly Fun Guide for entertainment listings in the city. 

Being a historic city, there is immense opportunity for sightseeing in Philadelphia. The city has a large public art collection which is the largest in the country. You can browse through them in South Street, Fairmount Park, Laurel Hill Cemetery and others. Interesting attractions include Eastern State Penitentiary, The Liberty Bell, Independence Hall and Philadelphia Museum of Art among many others. 

Independence Hall (Source: Eric Beato)

Philadelphia being about 221 km from Washington DC can be reached in about 3 hours. 

Detroit has been listed as one of the top ten party cities in the country by Maxim for its casinos and ordinance-free Sunday drinking. You can find much of its nightlife in downtown area, Ferndale and Royal Oak. In these areas, you will come across numerous bars, clubs and restaurants that are located within walking distance from each other. 

Slots anyone? (Source: a2gemma)

Suggestions by Frommers:

For more than 70 years, Detroiters have whiled away their evenings at Baker's Keyboard Lounge, 20510 Livernois (tel. 313/345-6300; www.bakerskeyboardlounge.com). Billing themselves as the 'world's oldest jazz club,' Baker's treats guests to the city's coolest live jazz and drinks every night but Monday. Downtown, the Majestic Theater building, 4120 Woodward Ave. (tel. 313/833-9700; www.majesticdetroit.com), is home to two favorite music venues: Garden Bowl, a 16-lane glow-in-the-dark bowling alley accompanied by Detroit's hottest DJs; and the Magic Stick upstairs, a bar and billiards establishment widely known as the city's finest live music venue (the White Stripes got their start here). Detroit is crazy for its sports, and one of its favorite sports bars is Nemo's, 1384 Michigan Ave. (tel. 313/965-3180; www.nemosdetroit.com).

 (Source: Nightlife in Detroit at Frommer's)

The casinos in Detroit are open 24 hours and provide exciting nightlife with slots, gaming tables, grand restaurants and live shows. The casinos include MGM Grand Detroit, MotorCity Casino and Greektown Casino. 

For sightseeing, you could explore the interesting historic neighborhoods of Detroit like the old neighborhood of Corktown, Greektown with myriads of Greek restaurants and Woodbridge for its Victorian style houses. The city boasts of interesting architecture which can be seen in Renaissance Center, Fisher Building, Wayne County Building and many more. 

Detroit - Renaissance Center (Source: Patricia Drury)

The traveling distance of Detroit from Washington DC is about 844 km, which will take about 9 and a half hour to cover by car.