Last trip we spent a week on each island and that wasn't enough.

In addition to Snowleopards advice...hire a moped.

Graciosa, anchor off the harbour, watch out for the cables, the locals will tell you if you are too close! Great bar restaurant just up the road past the harbour/slip, and have a walk through the side of the crater and down to the cave.

Terciera Angro, lovely town and harbour, you might see some whale boat racing, lovely coastal walks.

Sao miguel the double lakes/craters. Don't miss having a dip in the hot spring open air pool at Furnas

Have a good trip.