The public transporation system in Azores is really not at all meant for tourists. With there often only being two buses during the day; one in the morning to take locals into town and another in the evening to take them back to their homes, even relying on the bus system to take a daytrip is impractical. However, even without a form of public transportation to rely on, given the size of most of the islands, getting around should not be a problem. Walking is a great way to get around the city, or you can take a taxi if distance is a problem.