Bombing hills at night is where its at. In my city, in most the residential neiborhoods there are almost no cars out too. I'm always kind of worried about not seeing cracks or rocks, but streetlights help. Some of my favorite hills to bomb are the ones that are steep enough so you can build up a good speed, but mellow enough that you sort of stop accelerating at a certain point, and then you can just bomb them for multiple blocks, straight ahead with no powersliding. Although, powerslides are fun too.