I don't fly DL anymore, but have a hefty SkyMiles account that I am using for itineraries that are too expensive or too awkward for my primary carrier (hey, I live in SFO).
I was happy to get SFO-IAH-SJO and return in F on CO for the dates I wanted in March. I'll be on the beach in Manuel Antonio, Costa Rica for a week at the end of Winter, and will be travelling in style to and from!