Hard to avoid both hot summers and long, cold winters so where you fall on that line that should determine your search area.
Everywhere near the water is crowded now, but Eastern CT/Souther RI are still relatively nice and not crazy expensive (you're probably not overly sensitive to price moving from CA). Maine of course is nice and relatively cool but it's a long winter.
He lives in CA, pretty sure he won't be shocked by the taxes anywhere.