I found Southwest to be a lot higher for my March trip this year, as well. I generally find Southwest fares (from PHL) around the $100-$150 range, but this time it was $212 heading south and $350 going north. What I originally did was take the $212 going south and using some credits from an earlier flight to lessen the sting on that and booked a $169 going north, but from TPA instead of MCO. (I rent a car...the one way rental MCO to TPA was slightly more than MCO-MCO would be, but not much). I had enough SW points to pay for that one.
Now that my dates are really firm, I cancelled the TPA-PHL trip home and booked MCO-PHL on Frontier for $79 (of course, that became $129 once I added in a bag and a seat) and saved the Southwest points for another time. I'm still keeping an eye on that southbound $212, but its done nothing but go up since I booked it.