Known as the Windy City! No, its not because it's windy! It's because it was, and still is, the second largest city in the US and was full of politicians who were sarcastically know to be "long winded" and "full of hot air".
The LGBTQ neighborhood, which has famously been known as Boystown, is now called simply Northalsted; named after the street Halsted, which has a major strip of LGBTQ bars, restaurants, shops, and so much more. Another wonderful LGBTQ area is Andersonville.
Chicago has been known for some wild and fun parties, such as the annual International Leather Man contest which takes place Memorial Day weekend.
In downtown there is no desginated area of bars and nightlife, but if you are looking for a more downtown feel with a mixed crowd check out River Park, Old Town on Wells Street, and Roger's Park.
O'Hare International Airport (ORD) is the largest in Chicago. To get to downtown simply take the subway system using the the Blue Line.
Midway (MDW) is another airport you can fly into and can take the Orange Line right into downtown.
Chicago has an extensive train system, commonly known as the L Trains (elevated trains for being above ground). This system is the second largest in the US and can easily take you most anywhere you need in the city limits and surrounding neighborhoods; including Boystown! The middle is known as The Loop. It is a large rectangular intersection of all the train lines making it easy to transfer.
Hint, if you wanna go to Boystown you can get there by taking the Red or Brown Line to Belmont, or even closer one more stop on the Red Line to Addison.