Azure without car: Can São Miguel live well with bus and tour?

I don't drive and want to spend eight days in São Miguel in May. Ponta Delgada seems a good base, but the bus for lakes and paths have limited hours. I don't want to book a different tour every day or stay stuck in town when it rains. I am thinking of three organized excursions and a few days between the thermal baths, coast and walks reachable. Is it a balanced plan or is the car almost indispensable? I'm interested. above all a comparison based on recent experiences: indicated travel period, what really worked a…