The H440 is such a nice case, but I'm conflicted about windows for SLI.
Usually, you really want a nice fan or two on the side panel where the window is to blow directly onto the video cards.
However, it's a lot more complicated than that, and I don't think there's a best guide out there that describes everything.
There's positive and negative pressure for inside the case, blower type and open type gpu's, then with SLI the problems with each of those are compounded. Also, the ideas of "air flow", "turbulance", and "heat rises" aren't nearly as important as forced air.
The H440 has three fans in the front, which is great, and you can buy high quality fans for bottom intake and top/back exhaust.
Also, water cooling for the sli gpu's is an option, though much more expensive. But overall, I think it should work.