Going off the fiscal cliff would be great in one respect: the annual budget deficit would immediately be cut in half. But this can be done in much less damaging ways, and hence the need for a deal. Seems to me that the GOP should be insisting on only one thing: that the deal be deficit neutral. In other words, the deal should still result in the deficit being cut in half.
Instead, the GOP mantra seems to be: protect the rich. At least that's the way it's coming across via the mainstream media. I agree that the problem is essentially a spending problem, but there comes a time when you have to be concerned about messaging and take what you can get. At this point, a "deficit neutral" fight could be winnable. A "protect the millionaires" fight, not so much.