Any where in Japan is Awesome! just remember not to upset the "wa" (not sure that's how you spell it) don't yell for taxies, don't use your cell in an elevator, don't upset your host by not accepting a gift, always be polite to your elders, what we consider "hole in the wall dives" are some of the best places to eat and if you like history there's tons of really interesting places literally everywhere in Japan.
Edit : I personally like Kanagawa. Gorgeous forests, nice ppl, not too expensive.
Edit again : oh and the Kinosaki onsen (hot springs) is amazing also, worth the drive/ride from Kanagawa.