I spent a lot of time at the Pompidou Center during my time in Paris. And a lot of time in their bookstore.
I rode these escalators many a time to check out the exhibits. The views of Paris are not too bad from the top floor, either.
The Eiffel Tower through the window (and the rain).
Another great thing about the Pompidou Center is that the bookstore and the bathrooms don't require entrance to the museum. You just have to go through security. I'm not gonna lie--I totally took advantage of that a time or fifty.