[samokan]

why are concern about the dialect? if you know Japanese, you can speak it and they will understand you regardless of whatever dialect in the area is. if you speak proper Japanese to a local, they will speak to you in proper Japanese also. They know that you are a foreigner, so they do not expect you to speak the local dialect .

And Sendai, might be a good choice. I have never been there personally, but lots of my friends who have visited the area loved it, but it is cold there in winter.