What's the correct compensation for lost luggage?

I flew AA from LAX to Hawaii where my luggage was "lost" (and never recovered) back in mid-June and have only just received a cheque (check) for US $634.90....Is that right...seems a bit cheap? Aren't they party to the Montreal Convention, and if so shouldn't the compensation be much higher?

What about delayed bags - I was reunited with one a week later - again compensation applies as per Montreal Convention doesn't it?

AA sucks big time...I had to do all the paperwork and document all the items, etc., and I get a tiny fraction of their value - why bother documenting all the details then?? [sigh]