The biggest Mall in the world I’m told , this is a must visit. Bring your passport so you can claim tax back at the airport on your return, if your a tourist. This can certainly take up your entire day and there are affordable restaurants outside that have a view of both the Burj Khalifa and Dubai fountain. If you want to avoid crowds i would go during the day because the locals visit at night and it can get busy. Or go midday and do all your purchases so that by sun down you can sit and enjoy the lighting that adds to the experience of the Burj Khalifa and Dubai fountain.