If it were up to me, I would eliminate special elections for the House of Representatives entirely. They make sense when it comes to the Senate, where every state has only two senators and terms run six years, meaning a vacancy can leave a state without significant representation for an extended period of time. But when a congressman dies or retires and there's another election to fill that critical 1/435th portion of the lower house's lawmakers in a few months, do we really need to mobilize the state's electoral resources, spend millions of dollars, and get a bunch of retirees to haul themselves down to the polls, only to do it all again before you know it? Hardly.
The other objectionable thing about special elections is that because they're almost always the only election happening at that moment, they not only get an inordinate amount of attention, the results also get absurdly over-interpreted. This is a symptom of what we might call the Consequential Imperative among the press (note: if you have a better moniker for this that could propel me to the front rank of contemporary neologism-coiners, hit me up on Twitter). The Consequential Imperative is the impulse, the desire, the need to assert that whatever a journalist happens to be reporting on is very, very important. So for instance, if your editor sent you down to Florida to do a week's worth of stories on the special election that just concluded there, you are extremely unlikely to write that this election was a contest between a couple of bozos, and means next to nothing for national politics (unless you're Dave Weigel, who for some reason seems to be almost the only reporter capable of saying such a thing). It's the same impulse that causes every gaffe, polling blip, and faux-controversy of every campaign to be presented as though it could dramatically alter the outcome of the election, despite all the experience telling us it won't.