Luckily I didn't have to, nothing in the bag was of major value as it was an additional bag which covered our weekend shopping items in ATL.

Ya, under the convention, you really need to go to 3rd parties if you have expensive items checked:

"The Montreal Convention changes and generally increases the maximum liability of airlines for lost baggage to a fixed amount 1000 SDR (the amount in the Warsaw Convention is based on weight of the baggage)."

http://en.wikipedia.org/wiki/Montreal_Convention (better sources at linked here, but this gives the general meaning of the legislation)