nbujic
I know it seems a lot but that is because I gave lots of details but in fact it is not much and can be done quietly in 4 days. I agree 1000% that you should not do too much but many things I wrote about are very easy to combine.
For instance one day 'supposing you are near Opear/ Palais Royal)in the morning walk Rue Honoré/Faubourg St Honoré -crossing Place Vendome onto the Madeleine square. Coffee La Durée turn then to the right to do Gal Lafayette or Printemps -lunch Madeleine square (this is easily feasible in a morning (unless of course you want to do 3 hours shopping in Lafayette)
Then walk over to Left Bank (or direct Metro line to Rue du Bac) and do the left bank and stay on that side for dinner. That is only one day and you have 4 plus 4 nights!! Bear in mind that the Louvre is open 2 nights per week and Department stores as well (Thursdays)

I am a big fan of the Knopf Map Guides travel books. I would recommend this book for your trip to Paris because it breaks down the city by neighborhoods, it is a perfect size book to fit in your pocket,it has fold out maps by neighborhood with easy to read streets and list all of the sights, plus restaurants, cafes, stores, etc. for each area. It can help you to plan your visit in a more concise manner.
My favorite neighbhorhood is the Marais!

just topping this thread for Regina

Went to Paris this weekend, and the weather was fine. I'd say it was about 16 degrees celsius!