I tend to build my cities very organically, just building on whim as I go along. The auto road feature in zoning makes the roads more patterned than they would be if I put them all in by hand, but I usually zone in small sections so the grids don't always line up. I also would like to put in more diagonal roads because I think they make the city look more interesting. However, I tend to stay away from them because they waste space and it looks weird when the buildings are still at the same angle on a diagonal road. It would be nice if the buildings could turn to follow a diagonal road.