If you want to go up the Burj Khalifa, go to this site
https://tickets.atthetop.ae/eticketing/homepage.aspx
and prebook. It's usually fully booked every night.
For a good dinner, there's a nice restaurant in the Address hotel by the Dubai Mall that for 200 dirhams will get you all you can eat and drink. These kinds of deals are everywhere in Dubai and Abu Dhabi though. Many of them limit the types of drinks you can order, this one doesn't.
Swimming in the Gulf is pretty awesome... a natural body of water being that warm just seems ... wrong.
If you go to Dubai Mall/Burj Khalifa, it's a gruesome walk, especially if it's hot, from the Metro so take a taxi. They're dirt cheap in the UAE.
The sand dune thing is definitely a must-do if you're in the country for any length of time, but I don't know if you have the time.
Skiing in the Mall of the Emirates is surprisingly fun and affordable. The mall itself is something to see.
Go to the Irish Village and have a drink. Good fun place where you'll find lots of expats.
Head out to the tip of the Palm Jumeirah and visit the Palm Atlantis Hotel. You'll see all the sights on the way out, but honestly, if you're not going in the waterpark, there's not much to do once you're there. And it's pricey.
Rent a seadoo. So much fun. Just understand the shady dudes that rent them out will be shady. They'll tell you 150 AED for two hour or whatever and then they'll slap on another 200 AED when you return with a scratch on the machine that was already there. Still not a bad deal.
Head to old Dubai (Deira) and walk around the souks. Yeah, it's mostly junk that they sell, but if you want an authentic Middle East experience...
Go to Dubai Marina in Jebel Ali and walk around there.
REDVAN, where are you at in Abu Dhabi? I'm not there anymore, but my coworkers are living in Al Reef. Nice place to live, but soooo far from the city. We started out in Markaziyah.