Those of us on this board who live in the DC area are well aware of the quirks of finding low fares on the "real" airlines:
To go west, go to BWI where everyone matches Southwest.
To go north/south, go to IAD where everyone matches Air Trans and Metrojet.

But I was checking rt UA prices to Vegas late March/early April:
IAD: $660 (no surpise there)
BWI: $520 (kinda high)
PHL: $280 (huh???)

I checked PHL only on a lark, and was shocked to see the $240 savings over a southwest to southwest city pairing...is there some fierce competition to vegas from philly these days or what????