Listed below are a few guides I found for Paris.
The Paris Pass
seems to be a good value if you do several of the attractions listed. You can also download their guidebook for free. It's a large file and takes about 3 minutes but it is worth it if you still don't have a good idea of what to do in Paris. Thanks to Doug Baker for this handy tip!
Lonely Planet has extensive material for purchase but you can still glean some tidbits by reading the free stuff!