Spiff, there are some cheap Orbitz fares that aren't available on delta.com. The cheapest fare we could find elsewhere (incl. the other travel sites) was over $500 each - an L fare!! - to PDX in July. Delta is matching WN's companion fare sale only on Orbitz, as far as we can tell. The price for both of us was about $480, so we booked that way.
We called Delta in advance to make sure we'd both get our miles (esp. during double base mile season), and were told yes.
I'm a wimp, and I really didn't want to make that trip in coach, but the double base miles was too tempting. We did use DL's site to check for seats, and rebooked ourselves into exit row seats pdq.