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.
The hub is the center of the wheel, and typically houses a bearing, and is where the spokes meet. A hubless wheel (also known as a rim-rider or centerless wheel) is a type of wheel with no center hub. More specifically, the hub is actually almost as big as the wheel itself.