You will be thoroughly bored of the airport after a couple of hours, so best use the time for a welcome change of scene.

Lots of time to go into town, take the metro for a ride around Dubai (great for city landscape views on certain stretches of the line), maybe spend a while at Dubai Mall as already suggested. And/or have a stroll around the marina perhaps. So much to see in Dubai, it may not all be 'tasteful' - but at least it's different ; it would be a shame to just stay at an anonymous airport for all those hours........