Radisson chain is losing one of its Paris properties the Radisson Blu Ambassador hotel to Marriott on July 1, 2013. You still have today (June 30) to book it using Club Carlson points.
Considering the current Marriott properties in Paris and their award categories, it is likely that Marriott Opera Ambassador hotel will open as category 8 (40,000 points per night) or category 9 (45,000) points per night.
The point requirement using Club Carlson Gold Points is 50,000 points per night (if you can find any availability) or 75,000 points per night for a business class room (club room) that seems to be available even when paid rates are not loaded i.e. spring 2014. If you have Club Carlson credit card, you can redeem two nights for the price of one bringing the cost down to 25,000 or 37,500 points per night.
You earn far more Club Carlson points per night on average compared to Marriott ones, so it would be a better deal to redeem as a Radisson Blu property compared to Marriott one. You can read more about earning points on various hotel chains here and burning them here.
It seems that the leaving hotel has already blocked all regular award availability, but business class rooms can be still had at the 75K level.