Interesting subject. I would also like to know what others do and consider "must sees" while in Paris.
Our best memories of Paris are from just walking and walking !
However, some hight points were Sacre Couer , the Momartre area just behind, I personally enjoyed the huge department stores in Paris and their roof top cafes with magnificent rooftop views, Monet's home just outside Paris was among our favorite places, riding the Paris Metro, Eiffel Tower at night, the Opera house, Les Invalides where Napolean's sarcouphegus is resting and is now a military museum AND still a hospital, more walking and walking. We went to the Louvre and like you, found ourselves quite overwhelmed !! Not to mention the place was PACKED with people!! Took the little tour and left !!
Interesting you should mention Versailles. That was our biggest disppointment. Very little of the palace is open to the public. What is open is just about empty. To top it off the Hall of Mirrors was closed for renovation when we were there. The gardens are HUGE but nothing is marked in ANY language. It would be interesting (to me) to know the whys and wherefores about the many different statues, fountains, terraces, and small gardens, etc. We entered thru this kind of turnstyle gate to one side of the palace and were completely on our own. Not even a paper map or pamphlet. Confusing and BORING.
We were only in Paris one week and never got to take a bateau ride down the Seine. I can't wait to go back !! MG