Since moving to Seattle, Shannon and I have found public transportation suffices for most trips that cannot be walked. We still use taxis to get the airport (until Link opens) and walk to work, but excursions more than 2 miles from home usually involve Metro or Sound Transit buses. Two months after selling her car, we've only used Zipcar once.
Even without rail (we never need the streetcar), it has been unexpectedly pleasant thanks to comprehensive routes, generally short headways, and iPhone mapping.
What really makes the buses accessible though, has been the drivers. They're not only skilled, but generally friendly and thoughtful. They can be strict when they need to and clearly must focus on the task of driving, but often offer cheery salutations and goodbyes and helpful assistance to passengers. There's a systemic understanding that the job extends beyond piloting and includes customer service.
Recently, drivers have brought smiles to our faces often enough we've thought we should have brought cookies to share with them. Which led us to wonder if there's a Bus Driver Appreciation Day, when riders leave small gifts with their fare.
So, I nominate March 18th, when Pascal's Carosses a Cinq Sous started 347 years ago. If I don't need the bus that day, I'll just make an excuse to take one via the tunnel for lunch and leave each driver something to say "thanks".