Short layover (3-6 hours, in airport)
Dubai International Airport has 4 free lounges if no Priority Pass. Marhaba Lounge (paid, 200 AED/hour). Shop, eat, rest. No visa needed.
Long layover (8-12 hours, exit airport)
UAE 96-hour transit visa available for most nationalities. Sheikh Zayed Mosque or Burj Khalifa observation deck. Atlantis aquarium. Return to airport 4 hours before flight.
24-hour stopover
Sheikh Zayed Grand Mosque (Abu Dhabi day-trip) OR Burj Khalifa + Dubai Mall + Old Dubai (Al Fahidi + Spice Souk + Dubai Creek abra ride). Dinner at Pierchic or affordable Lebanese.
48-hour stopover
Add desert safari (sunset 4-hour). Then Yas Island Abu Dhabi day-trip (Ferrari World + Louvre Abu Dhabi). Or second-day relaxed beach time at Kite Beach + JBR walk.
72-hour stopover
Add Hatta Mountains day-trip (dam + kayaking, 2 hours from Dubai). Or detailed Sheikh Zayed + Louvre Abu Dhabi + Yas Marina full Abu Dhabi day. Spa or rooftop pool day on third day.