How about a 1 Day and a much longer window, maybe 365 days, to satisfy the long tail reward market (more like YouTube)?

That's an interesting thought. Not sure if there would be computational limits for the witnesses to calculate rewards for that many active posts, but from a functional perspective there's definitely an argument to make for it.

How would the Upvu, Upex etc mega-voted posts fit into this?

Not sure, but I guess that's a small (highly visible) percent of the total. I guess they'd continue to stick out like a sore thumb, but maybe it would give investors the information they need to shift from short-term to long-term strategies.