Each program is unique. And each is a musical exploration. Some suggest story lines. Some evoke the seasons. It is, perhaps, easier to define the show by what you won't hear, than by what you might hear.
Thrash rock is generally out.
Lounge lizard music has only made it a few times, generally played at the wrong speed. Contemporary hits rarely make it until at least a decade after they've been forgotten. ABBA's out, though Swedish goat calls have made it, usually played over some South African piano music. Kenny G is out. And anything Harwood used to play in a polka band in New England is out.