Tracy--in case Charlie doesn't see your question---AF stands for Air France. They fly direct from Seattle to Paris.
As for buying insurance from the airline, the one time I looked into that when I bought air tickets, it turned out the specific policy (offered by Allianz) was not available to Washington residents.
If you do find one that is, compare the price to policies offered at insuremytrip.com before you buy. Also consider whether you really need the insurance---how much have you invested in prepaid, non-refundable expenses? If all you have there is the airline tickets, look closely at the airline's change/cancellation policy. Although non-refundable tickets are exactly that, some airlines will give you credit for a future flight if illness causes you to cancel your trip. There is a change fee involved, but you do not lose the whole value of the ticket.
If you have other expenses involved, such as a prepaid tour, or apartment rental, then trip insurance may be worthwhile.