Osaka, Kyoto... or somewhere else?

Looking for a luxury experience for the second half of my Japan trip in November. My husband and I will be staying in Tokyo for 4 nights and looking to spend the next 6 elsewhere. Most people suggest Osaka and/or Kyoto, but not sure if it's worth staying in one vs the other (and doing day trips?) or if another city/experience is better. Open to an onsen/ryoken and flights to other areas of the country.

Thank you in advance!