Well you are trying..lol.. but this would get more answers if you booked under Destination Forums, left colum on forums page, under "France" rather then the "Reviews of Hotels" section.. but no worries.
Ok, I have been to Nice and stayed in a nice hotel.. but its not 5 star.. not even 4, so will not bore you with details.
If I was going to find an expensive hotel I would look at the reviews on tripadvisor.com.. AND I would also look on booking.com. The reviews on tripadivsor have a section where folks can post actual photos from their stay.. so much better then the professional photos a hotel releases.. more realistic. and the reviews on booking.com have a review section for each hotel that are only posted by those who have actually stayed at the hotel.. ( sometimes folks can "plant" fake reviews on tripadvisor.com and unless you are willing to read carefully it may be hard for you to tell.. )
Pop in your dates and see what comes up.. its a starting point..you do not have to book via a booking site.. I would then go to the hotels own website.. compare rates ( can be cheaper on either site depending ) and just book either direct or via booking.com based on price and room wanted.
Nice is not super large .. anywhere although we were a few blocks from promenade ( beach ) we still found it easy to walk everywhere we wanted to go..
While in Nice definitely hop bus or trains and explore surrounding cities and towns.. Monaco is only an hour away by bus.. less by car or train I imagine.
avirosemail.. you are wicked.. lol