The longer road is better for ocean views; the shorter road is better for hiking to the highest point on the island, Mount Brandaris. The park closes at 5 pm, so plan accordingly.
Other tips: each visitor must purchase a $25 permit that's valid for the calendar year. However if you bring the STINAPA windsurfing permit you bought for $10, you only have to pay the $15 difference. Also, the roads are rough and some rental car agencies don't want you to take ordinary passenger cars into the park. On my recent visit we did indeed blow a tire. :-(