Portland, Oregon has an AMAZING public transit system called "Tri-Met"
http://trimet.org/
It is not perfect, but it works wonderfully!
We have a MAX (light Rail system) that goes all over the place. We have buses EVERYWHERE and busy routes run as often as every 10 minutes.
Our city is divided into 3 zones and you pay based on how many zones you are traveling through. Children 7 and under are free, and adults cost $1.75 for 1-2 zones and $2.05 for all 3 zones. You get a Transfer Ticket that you use to switch to other buses (or the MAX) that is good for at least 2 hours (longer depending on the driver

).
We also have "Fareless Square" Which is a fairly large area that covers the majority of the downtown area and even across the bridge a bit where you can ride for free.
Oh-and a lot of the buses are run on BioDiesel as well....

Basically I can take myself and 2 kids across town and back for $1.75 and not spend my whole day waiting for buses.
We are very spoiled here.
.