There is something moral to design things that will last for a very long time, for me it is important to visit the modernists. It is always stimulating and joyfull to visit the permanent collection of the Centre Pompidou.
It's always good to check out what's happening in Fondation Cartier. They have lots of really good exhibitions of modern art, and the gallery itself is very beautiful. Perfect for seeing works you already know as well as discovering new artists and inspirations.