[KaVir]

The exploration reward in GW2 was actually an afterthought. I'd already planned to have one task per area, but I didn't want to overwhelm newbies with a huge list of tasks, so I decided it would be better to hide them until they'd been unlocked. The easiest way to do that was to make them multi-stage tasks that are hidden until the first stage has been completed, and then have the first stage completed by visiting an area. As the task system already had a built-in mechanism for rewards, I decided just to give 100 exp per area.

Obviously there are other benefits in discovering new areas as well, but assigning a reward turns exploration into a series of clear short-term goals with direct tangible benefits. You don't have to award exp in this fashion of course, but IMO it really is important to have short-term goals as well as long-term ones, and this is quite an effective way of doing it.