NW has luggage transfer arrangement with AS but that is only true for domestic flights only, as in your case your International flight is terminating at Seattle which will become your port of entry so you have to claim your baggage, clear custom, immigration then you will have to go to AS counter to rebook your baggage.In SEA custom/immigration doesn't take more than 30 minutes in normal. Your 2 hrs connection time is very much sufficient to make a connetion to LAX by AS.