From my time living in DC, I've seen plenty of politicians in both F and Y. For the most part, they earn status the same way we do, though, as noted, there are apparently some comps to invitation-only status levels. Some do decline upgrades for the sake of appearances. Upgrades aren't, to my knowledge, routinely comped at DCA for members of Congress -- most of them fly home every weekend and many wind up on the same flights heading for connections home, so upgrades are cleared per normal procedures.
Your rookie would probably be better off going with AA to DFW or ORD on the way to OKC on the basis of flight frequency; a Plat challenge would get him status quickly. Just about everyone on the Hill uses DCA when they can; they get free parking there and you can make the drive in just a few minutes (or take Metro from station near the House office buildings). Getting to either IAD or BWI is a pain in the rear that kills most of the time saved by taking a non-stop.
personally, I prefer UA's nonstop flights between IAD and OKC. It's on a "tiny" regional jet with first, economy+ and cattle class.
I can't remember if they had one or two nonstops per day.... anything is better than having to connect in DFW and ORD.
