Versaille or Chartres
 

You will love Paris, I'm sure. Now, I've been to Versaille twice and find it daunting, exhausting, crowded, overwhelming, etc. I wish I had gone to Chartre instead, and next time in Paris, I will. Of course, it would be better if someone answers who has been to both, but I don't like Versaille. I think there is an icky feel to it.

I have not been to either, but my experience in Europe has been to take the cathedral over the palace. Palaces are magnificent but overdone with gilt, upholstery, and mirrors. Catherals tell a story, usually build over decades or centuries. I much prefer them. The great American historian wrote a masterpice about Mont Saint Michel and Chartres. Hope to see them both some day.
Enjoy France.

PS. Historican was Henry Adams.

You might think of skipping both Versailles and Chartres if you have only 4 days in Paris--that's barely enough to skim the surface and see some of the major sights in the city.

If you really want to get out of Paris, however, Chartres would work best as a half day there is adequate to see the magnificent cathedral and the medieval precincts. Versailles really requires a full day.

I have been to both (three time to Chartres). The cathedral was however not at its peak when I last visited in 2003 because the windows were being cleaned. This meant that a whole stained glass window was removed, and was temporarily replaced by a clear window. This had the effect of severely altering the light inside the cathedral, diminishing the effect of the remaining stained glass. I have visited about 30+ of the major cathedrals in France, and would place Chartres at about No. 5 when it is in its normal condition.
Versailles is as described by a poster above, and gives an excellent example of WHY the French had to have a revolution. The French monarchy obviously had an over-exaggerated idea of its own importance, and Versailles certainly testifies to that.