Thank you both est-gratuite and rdlmitedu !

I took a look of the pictures of both Sheraton and Ren, have to agree the Sheraton lounge looks a lot nicer both the furnishing and the views outside.
The standard rooms also look nicer.
I think I would book the last night in Zurich now, then decide whether we would spend 2 nights at Zurich or only the last night.
I want to use my husband's FN cert which expires earlier than the remaining certs, but he is only Silver. Wonder if this property would give give the benefits based on the higher tier guest or based strictly on the account used to book. Most Asian properties it is the former. BonVoy reps also told me it was the former practice.