I'm in Spokane, WA. We have a bunch of people here that grow Cattleyas too, but it has to be done with artificial lighting.
Where I'm at right now, I just use a few CFLs to supplement the sunlight that my orchids aren't getting because of our shorter days. I've got a variety of different plants that are supposedly shade loving and "good windowsill growers" and I'm gonna go through this winter and see what lives and what thrives. Whatever I have that's thriving, I'll buy more of in the spring. What's not thriving, I will sell or trade to someone else, if its still alive.
My daughter is very interested in growing cattleyas. She has one and she has a wish list with several of them on it. I expect that when she gets her first apartment, one of the first things she'll do, is get a light stand for growing some cattleyas.