I'm currently in Paris and doing 4 nights at the Peninsula in a Junior Suite and 4 nights at the Hotel de Crillon in a Premiere Suite (I think I got upgraded? -- I booked a Deluxe but it doesn't look the same as on the website).
I just checked in to Crillon and my first impression is that the decor, finishes and room hardware are great. I wanted to stay there in addition to the Pen because Crillon seemed to strike a balance between Pen's "modern / high end but not very French in character" and something like Ritz which is a bit too old world / gilded for my taste. Plus it's nice to try a different location.
When I checked in to the Peninsula Paris I had deja vu (how French :-) recalling the Peninsula Tokyo room layout, and hardware (same template but updated), etc. Other than the windows w/ awnings, the Peninsula Paris feels like it could be a high end luxury hotel room in any major city (a fantastic and comfortable one I'd be happy to stay in though).
But I will say at Crillon I miss the practicality of the Peninsula in terms of total space, but especially closet space and desk space. There are quite a few closets but they are all very narrow so I can't put my luggage in them laying out flat. Also, there is not really any obvious work desk in this room. But I've only checked in to Crillon today so I'll have more to compare and contrast after I try room service, etc. [Re: room service -- perusing the menu I noticed Crillon only charges 38 EUR for a cheeseburger vs. Pen's laughable 52 EUR, despite Crillon charging more for rooms in general :-)]