If you were to follow the values that were data-mined for the exp curve from 50-60, I wouldn't think just hanging in Northern Thanalan would be the greatest of ideas.

For context, from 1-50, you need to earn a cumulative 8.2 million points of exp.

If the values found are to be true, to go from 50-60 is about 10.5 million points of exp. That is more than double the road to 50 from 1! Not to mention that until you get your first level 60, you are also losing on your passive 50% exp bonus. Overall, you'd probably be better off just hitting the new content, at least for your first level 60. If you follow the main scenario, grind out a couple of the dungeons, and hit each questing zone, you'd probably be hitting it pretty naturally.