I have stayed at Beniya Mukayu, but I'm afraid it was over 15 years ago and I don't have particularly detailed memories of the stay, other than that I enjoyed it. IIRC, the area directly around Beniya Mukayu is not very interesting, so you'll definitely want to go into Kanazawa or elsewhere for sightseeing.

I am sure that a ryokan of that level would make every effort not to give you the same dinner for two nights in a row, so I wouldn't be too concerned about that--perhaps it's more a question of how much traveling you want to have to do during the day, ie you might want to find a ryokan more centrally located to where you want to do your sightseeing.