Here's the real clincher:
The generators of diversity
"To generate exuberant diversity in a city's streets and districts, four conditions are indispensable:
1. The district, and indeed as many of its internal parts as possible, must serve more than one primary function; preferably more than two. These must insure the presence of people who go outdoors on different schedules and are in the place for different purposes, but who are able to use many facilities in common.
2. Most blocks must be short; that is, streets and opportunities to turn corners must be frequent.
3. The district must mingle buildings that vary in age and condition; including a good proportion of old ones so that they vary in the economic yield they must produce. This mingling must be fairly close-grained.
4. There must be sufficiently dense concentration of people, for whatever purposes they may be there. This includes dense concentrations ... of people who are there because of residence.
The necessity for these four conditions is the most important point this book has to make. In combination, these conditions create effective economic pools of use" (151).
Downtown Danville has points 1, 2, and 3, and notably, is a major asset to the town region--a justifiable magnet for folks in the suburbs radiating around it who get bored by all the dullness. Apart from Walnut Creek, it is probably the only town center on the 680 corridor built for pedestrians. Maybe parts of Pleasanton and Livermore would take offense at that. Though I cannot speak for its brethren, I know Dt Danville was laid out before the car. Hence, the short blocks and sidewalk building frontages.
Pretty much everything else around it is chain retail behind acres of parking. Progress!