One of the city's premier shopping centres, the Abu Dhabi Mall, is adjacent to the Beach Rotana Hotel. As in much of the middle east, shopping centres are big "hang-outs", particularly in Abu Dhabi, where there is little entertainment (unlike Dubai) during the hot summer months. The mall itself has many luxury boutiques and cafés.
This is one of the larger malls in Abu Dhabi and is located right in the city centre. It has all the typical "mall brands", a food court and a few individual shops as well. The mall is definitely a nice time-pass if you have a few hours to kill in AD.
Their website is not up and running yet, but I've provided the link below nonetheless.