Yes, by all means a car is necessary. How long for San Miguel? Hmm, IMO
minimum 3 days but one or two more would work depending on weather of course.
Some of the Islands have a bit better weather and check the climate data.
A trip to Furnas is a must--that was most of one day. Don't miss the scenic
overlooks that have/had a full time gardeners. We hiked around Lake Azul or
Verde to try and get soe shots and brought a picnic lunch. There was a spot
near one of the lakes with tables--only ones there. We stayed in Villa France
do Campo in a rambling rebuilt convent. Pico was very very cool. I want to
see Flores and hike there and exercise my Zuikos.
Themed Olympus Photo Exhibition: http://www.tope.nl/