Doesn't the blog post below address hotel and inn yukata?
Yukata Underwear: Necessity, Or Not? Do you have to wear underwear with yukata?
http://blog.livedoor.jp/auberginefle.../51885528.html
Under the headings:
1) Are you wearing your yukata as a bathrobe or sleepwear at home or alone in a hotel room?
2) Are you wearing your yukata at an Inn or Onsen spa around other people?