Was yours a mtc issue or weather? If mtc then Delta will provide accommodation/compensation but if weather their liability is limited (as is every other US carrier).
My problem is that DL will sometimes classify delays as weather related when weather wasn't a factor at all for any other carrier out of RDC that day (recently happened to me RDC-SLC-ANC; got stranded in SLC).
I understand delays at earlier stations can cause trouble, but if your going to claim that its weather related when no other carrier had cancel flights or had long delays due to a LITTLE rain.