My company views working from home as being entirely a benefit to the employee so my salary is commensurate with salaries where my company is based in a lower COL area. A friend's company bases the salary on the location of the employee. Similar companies in the same industry, totally different policies.
That said, if it were me in your shoes, I'd go for the DC salary then negotiate work from home when you're ready to move to the lower cost of living area. There is a much higher chance of you keeping the larger DC salary when you move. Unless a company has a set regional COL salary adjustment policy (which isn't that common) they aren't likely to reduce your salary to reflect the cheaper COL.