They should really do away with the fees as more and more people will now try to stash their excessively large suitcases in the overhead bin (If you fly to/from DCA, you know about the lack of bin space because of the suitcases). Because of that, the F/As would then check the bags of the last people to board, regardless of bag size, and make them pay the fee.

In fact, on one trip to PTY, we were on a 757-200 from ATL and because of the amount of suitcases in the overhead bins, the F/As were making people check their bags, as there was no room on board.

US Airways was bad with their fees, but not this bad