Two days just wandering around on my own and with  friends. 360° panoramic view from the roof of Institut du Monde Arabe gave me good understanding of the city layout, the view is really good.
View from rooftop observation deck at Institut du Monde Arabe
Day trip with ☞ France Tourisme (6 hours of driving to/from the Valley and 6 hours of visiting the castles): Paris/Louvre ➜ ☞ Château de Chenonceau ➜  ☞ Château de Cheverny ➜ ☞ Château de Chambord ➜ Paris/Louvre.  I wanted to visit  Amboise and  Leonardo da Vinci at ☞ Château du Clos, but no other people signed-up and the agency offered alternative tour with Cheverny instead. Overestimated distances in Paris, walked over to the pick-up place way too early and had plenty of time for early morning photos. I had the front seat in the minibus, nice weather and good views.
The day was all about  ☞ Versaillles. Took M4 to Gare Montparnasse and local, but fast non-stop train. No railroad strike that day. I was very lucky as my friend works at Versailles and gave me a private tour. We started at the Royal Chapel, visited the upstairs quarters, joined tourist stream to visit main atractions, returned to the Chapel. I then made a big loop zig-zagging through the park and gardens, watching fountain show, walking to Orangerie at the end.
Mirror Basin
We walked through town a bit, found a nice restaurant for dinner, and returned by RERC Â and bus to the city center. I walked by Notre Dame, Hotel de Ville and Pompidou Center to my place.