Housing in Paris, ideas?

Bonjour bloggers,

A little background:
I am moving to France in the fall with my soon-to-be husband. I have job offers in Paris, but I would consider living in Lyon or Strasbourg. He is French-EUer, holds a passport--all of that but grew up in the States.


Mon Question:
Are there any good sites we should check out to get housing? Or really expensive or trashy neighborhoods to avoid/flock to/run screaming from?


curious
-E