The benefits of walkable neighborhoods include health and happiness, improved environment and community. Walkable neighborhoods also command high real estate value.
Cycling just makes people happy. Bikes can be a viable form of transportation and cities that build safe cycling infrastructure allow people to feel even happier, healthier and reduces pollution.
Cities that provide efficient public transit reduces individuals sitting in traffic and the stress that goes with it. Why not multi-task while by reading a book on your way to work?