Are they looking Southern Coastal or inland?

Inland in a sense that they are not looking for a beach-front
property, but for gardening only. At the same time they would
stronlgly prefer a wetter and colder climat, while it should be within
a day's drive from San-Francisco. What place would you recommend ?

I did not quite understand what you meant by "they should seriously
consider renting/leasing it out to responsible folks" ? Thay are
planning to live there, or at least visit it every 2 weeks, all the
time from the late spring to early fall.