I have stayed in a Junior Suite at the Westin Paris on two occasions. I did not feel it was worth the points or the Euros spent. Both rooms were large for European standards, but the rooms were a bit disappointing. One room had a separate living room (open to bedroom) and the other was just a large room configuration. We are platinum and they told us both times that they do not upgrade from a junior suite. (I however have read that people do get upgraded from junior suites to full suites, just not us.)
On several occasions I have booked a junior suite at the Prince de Galles but have never stayed in one as they always upgraded us to a full suite. Much nicer in our opinion.
But how did the Jr Suite compare to a standard room? The OP is judging whether it's worth a measly 2,500 extra points a night to be in a Jr Suite over a standard room. I've never stayed in this particular hotel, but generally find the Jr Suite awards to be very good value in Europe. There's usually a substantial difference in room rate over the standard room which you are getting for a very small incremental increase in points.