We visited the castle and theToyota Museum and took a tour of the Toyota auto factory. You'll need a reservation for the factory tour. For me, the factory was most interesting. http://www.toyota.co.jp/en/about_toy...our/index.html
We stayed at the Nagoya-eki Shinkansen guchi in March. Guests are normally not allowed in the rooms between 1000 and 1600-The staff cleans all the rooms during that period. We asked for the "eco" option which means that the staff doesn't enter your room but hangs a bag of towels and consumables on the door knob. There was a small "discount" and we were allowed to enter, exit and occupy our room at any time during the cleaning period.