This is a slight tangent, but for future reference, I just want to point out that regardless of an airline's policies, some airports may have a policy that bags can't be checked through on overnight connections. I got burned by this at JFK once on an 8 hour overnight connection on AS (despite AS' policy being that they would check it through). I'm not sure if other airports have this policy but it's worth checking (my understanding is that the same thing would have happened on AA, or any other airline, since it was an airport policy overriding the airline policy)