There are some IC's that are better than some Ritz C's, and if you book a top suite at a top IC it is definitely a luxury experience. However we have a special forum here for IHG and Starwood for the St. Regis properties. So you would best take those discussions there.
It's been a long time since I was in Osaka, but I thought the Prince hotel was nice for a business class hotel, and there are some luxury Ryokan's in Osaka.