For those of us who don't (yet) have ExpertFlyer subscriptions:

I want to go standby on a LGA-CLT flight tomorrow morning. The US website shows "Sold Out" if I want to book a ticket on one of the flights; Expedia, however, shows 5 seats available on at least one of them.

Who's right?

Also, for some first class cabins, the US website states, "Sold Out"; for others; "Unavailable". Is there any way to read between the lines between those two expressions and tell what the status of any upgrades would be?

Thanks.