Due to some missed connections, we had to spend a night at Abu Dhabi airport. Here are some options for you to consider:
Request for lounge access. The airport has a nice lounge with hot food, shower facility and comfortable lounge chairs. You can request the airport staff to grant passes, and if you are lucky, they may oblige.
Depending on your nationality, if you are allowed to exit the airport, you may research some options about nightlife in Abu Dhabi. Alternately, Dubai is just 2 hours away, offering more options.
Vagabond around the airport. Obviously the last resort, but when we were there 2 years ago, they had a real life Formula 1 display, which caught my attention for an hour or so...