Hey, 1000th post
Since I've tried to use this thread to figure out how to spend a long layover at DXB, I thought I'd update it with current information.
There are two lounges, both near gate 126, while UA977 left from 109' which is a bit of a schlep. First and *G use the LH lounge. It's small, but comfortable and the food and booze is what I've come to expect at LH lounges. There are no showers. It opens at 7, and I was really the only one there until about 9:30. C customers use the Marhaba lounge across the terminal, it's got better hours but doesn't look as nice.
For showers, there are public shower rooms in terminal 3, which are free but attended, and you have to provide your own towel. The G-Force club at the Dubai International Hotel a gate 117 is exactly as DEN describes, except gym and shower is now $21. The gym is 30 by 30 feet or so, and has basic workout equipment in good condition, though the only view of the tarmac is back through the door. Between 5 and 7pm, I was the only one there. The showers were good--better than my gym at home--and it looks like the lobby of the hotel is a good alternative to a pay lounge, as it has a view of the tarmac and a bar that is quiet.
To burn some time, I took the Big Bus transit tour. Buses leave about every two hours, and they escorted me quickly from the terminal through immigration to the bus (it' about half a mile, so if no one is at the desk, that may be where they are). It's a slow 2 hour drive around the city, hitting architectural highlights. They dropped me back at terminal 1 on request, but it is a real odyssey to get back to the gates, so be sure to allow time.