Just thought I'd drop a line about what we decided to do RE: airport shuttle that provides infant car seats.
We ended up booking through
http://www.pariswebservices.com/
at the last minute (Tues eve for Wed eve arrival) and were very happy with the service.
You need a credit card to make the booking, but they don't charge it because you pay the driver cash. We were quoted €75 for our arrival trip and €65 for the departure when we made the booking. This included the car seat and the 'Rick Steves' discount (check his website). The driver was there with a sign for us at customs, helped us with our luggage, got ourselves and baby situated (car seat as promised), made friendly chat and showed us the sites on the way, helped again with luggage and the key codes for the apartment. He was there 20 minutes early, just waiting outside until we were ready, and was pleasant and helpful at 7am on a Sunday!
This was an expense we hadn't anticiapated, but we would use the service again because it made the trip sooooo much easier and less stressful for our family!