Upvote:2
It all depends on what you like to do! You probably want to go and visit the Burj Khalifa. The tallest tower in the world is a must see. If you don't want to go to the top, at least, check it out from the lake. There is a nice view.
Then, if you get there and you like shopping, check out the Dubai Mall. If you want to see the old Dubai, then while going back to the airport, stop by Deira old city. Stroll in the small streets of the spice and gold souks.
If you prefer to refresh, check out Ski Dubai at the Mall of Emirates. The Mall of Emirates is also a great place for shopping. There are some half days city tours. You'll easily find them on websites like this one on Viator.
On my website, I have also listed a lot of additional activities available in Dubai. Listing these here as my website is in French :