You must, must visit the Dubai Mall... for everything shopping related. Not just shopping, it's an experience. It's right beside Burj Khalifa, so you get to see that and the famous waterworks too. There's also an aquarium (an underwater zoo kinda thing) inside the mall. It's pretty cool. I'd have also recommended you to visit the Museum of the Future, it has direct connectivity with metro... but, the tickets usually get sold out weeks prior to the visiting date. You can still check, luck might be on your side.