You can find walkable, safe neighborhoods all across the city, so it will likely come down to the location of your work, and the type of lifestyle you prefer (laid back, in the scene, family life, etc.). I live on the west side myself, so I'll speak to this area.
What is a Concave Wheel? Concave Technology takes the center of the wheel and dips inwards to give it that bowl effect. Rather than exaggerating a bigger lip for the back wheel, and a smaller lip for the front. Concave wheels emphasize the concavity of the rear wheel to differentiate from the front wheel.
A concave polygon is a polygon that is not convex. A simple polygon is concave iff at least one of its internal angles is greater than . An example of a non-simple (self-intersecting) polygon is a star polygon. A concave polygon must have at least four sides. From MathWorld--A Wolfram Web Resource.