With eight hours to kill (subject to meeting any visa requirements) I would always recommend a poolside lunch at a nearby hotel, where of course you would also have access to showers etc. Many properties are happy to extend these benefits to non-guests. Far more relaxing than any airport lounge

Alternatively - if not already familiar with Dubai itself - you could see quite a bit of the place, including many key sights, in the available time.

Ps ....this of course may not be the best plan if your transit is overnight ....(?) !