Sorry for the very late reply. All your suggestions where excellent, especially since I didn't know who they were before meeting them, the suggestions covered all the important things.
Sadly the clouds didn't cooperate at all. Just as it grew dark a cold front moved in (after a gloriously sunny and cloudless day) and the sky clouded over completely.
At least now I'll know what to show them or other NH visitors when they come around.
BTW: Only one of them had looked through a telescope before so I reckon most anything would have wowed them.