I think you should spend your last night at Gora Kadan, as it is a totally diffetent experience and arguably even nicer than the Hyatt, although I love both. I think two nights at HR Hakone followed by one at Gora Kadan is an ideal combination and length of stay.

About HR Hakone, I recommend booking at least a Deluxe twin room for the views and added space. If this is an award reservation you can confirm a higher category by paying the difference in rate. Because of the small size of this propety and its popularity, it is often fully booked. One should never count on a complimentary upgrade as a Diamond, especially on weekends and holidays.