Couple of things I would look at for rough roads- sand and ease of maintenance
Bikes with an internal hub for the gears and disc brakes.
Although this is classed as a City bike- It will take rough roads and providing you don't want to ride in muddy conditions- even the tyres will work on loose stuff.
http://www.giant-bicycles.com/en-US/...ek/7342/44056/
And if a bit over the price range- then the lower versions will still work