8 days are not too much to spend in Paris.
Lots of good suggestions as to day trips here (add Fontainebleau and if you make ONLY 1 DAY TRIP MAKE IT TO VERSAILLES)
One thing not mentioned here regarding visiting the Loire Valley unless you go with a tour company, the TGV runs only to Tours a wonderful city worth visiting on its own.
TO SEE THE CHATEAUX YOU MUST RENT A CAR.

Suggest you visit the ones mentioned before Chambord is a bit 'cold' since it has little furniture but has a good equestriian show. Include Cheverny (its quite close to Chennonceau)and Villandry which has the most amazing geometric gardens in the Loire Valley, all the above are with 30 mins driving (including time for getting lost) from Tours.
Enjoy



[This message has been edited by MIKESILV (edited 03-12-2001).]