What to do in Dubai for 20 hours?
 

What is there to do in Dubai for 20 hours? (besides hanging out at the BA Terrace lounge, or sleeping at the transit hotel)

Anyone who did a "Dubai turnaround" participate in any "1 Day City Tours" (if they exist)?

I would most certainly NOT spend 20 hours at Terrace lounge at DXB. It is a typical terrace lounge; rather crowded and no sleeping facility, I think. You can think you are under the beautiful deck umbrella in the Province designed by Sir Terrace Conran while at this busy DXB terminal, of course.

You might consider visiting their 6-star hotel, Buji Al Arab, to see what on earth all the buzz is about this property. It is a sign of the oil money now serving newer oil money from Russia and the Cenral Asian countries. From outside, its futuristic design looks awesome indeed, and once inside,
it is tackier than most hotels in Las Vegas.
The restaurant called Sky Lounge at the top, however, offers a surprisingly competent food, IMHO.

Visit the Gold Souk for some of the best prices for gold jewelry.

Gold souk and shopping are excellent suggestions. Dubai is a pretty cool place, and even though it's been 5 or so years since I was there last I'm sure it's still great. The gold souk is in "downtown" Dubai near the creek. You could also get up to Sharjah to go to the rug souk. Lotsa fun.

There are numerous tour companies that I'm sure could arrange all sorts of desert tours, souk tours, Fujairah tours, oasis tours. Have fun! Maybe you can arrange a spa day the Burj.