I was going down the path of skateboarding as a profession before I succumbed to my true computer geek nature. Not only do you notice the terrain - how steep is that hill? How big is that jump? Can you slide on that? Are there pebbles around that could stop my wheels or is it well swept? Are there any marks indicating that someone has skated that successfully before? You also take note of things like - Is this in front of a business that would complain about me being there? How many people are walking by? How close is it to traffic? .. Besides having fun, you have to take into account the risk of being complained about and dealing with law enforcement.