If I had that situation, I'd travel to all the cities I want to see but haven't yet, like Paris, Rome, Madrid, Rio (and lots of others) before deciding. San Diego would also be a contender, because of the weather and its proximity to both beach and mountains. Ditto for Santiago, Chile. And then I'd probably pick more than one!
Of the places I've been, Portland, OR could be a contender, as well as Amsterdam and San Francisco.
Actually...we might well end up right where we are, in the general orbit of NYC. Culturally, it can't be beat, our neighborhood is quiet and safe, walkable, bike-able, and it's easy to get to the city from here with no car required. We get all 4 seasons, but not too much of any of them...I guess Dorothy was right — there really IS no place like home!