We're a family of 4 (with college age kids), making our first trip to Japan next week. We have a plan for 4 nights in Tokyo, 2 in Kyoto, then have 2 nights free before returning to Tokyo for our last night. Takayama gets good reviews everywhere I look, but I'm hoping for input about other possibilities, such as a seaside village that has an authentic, unspoiled feel. We're not big on museums or shopping, but love food, walking, looking at architecture.

About Takayama: do we need to get out of the town and into someplace like Shirakawa-go in order to see the more rural side of Japan? Is 3 hours roundtrip on a bus worth it to see the village (especially given that we'll be there the weekend before Christmas - too cold? closed down?) Would 2 nights in Takayama be about right, or would it make more sense to travel Kyoto-Kanazawa-Takayama, spending just one night each in those places? I don't want to stack up too much travel time, but I want to avoid sitting around wondering if we devoted too much time to Takayama.

I thought about Hakone, but it seems like natural beauty and the spa life are the real draw there. Given the weather, I think we'd rather have less gazing and more to explore - neat villages, shrines, etc. Please tell me if I'm wrong about Hakone - is it really a must see?

Any other suggestions that would be fairly convenient to the Kyoto to Tokyo travel route? Coastal locations, especially, or UNESCO heritage sites?
Thanks in advance - a bit of panic here trying to make a decision!