Saadiyat Island there’s a couple of art exhibitions going around there. The Monte Carlo Beach Club is a must. It’s accessible from downtown Abu Dhabi easily. (http://www.montecarlobeachclub.ae/)
Try the world’s fastest roller coaster at Ferrari World. It’s fun for a whole day.
Get a superb view of the city’s skyline at the Corniche Waterfront.
Visit the tremendous Sheikh Zayed Grand Mosque. It features the world’s largest hand knotted carpet, 82 domes, over a 1,000 columns,and the worlds largest 24 carat gold gilded chandeliers. (dresscode: http://www.szgmc.ae/en/img/Mosque-Manners.jpg)