Update to this: First off, I discovered that our AC DOES have a "circulate" setting on the thermostat, so I set it to that. Closed off most (but not all) vents on the bottom two floors. Upper floor vents wide open.

Put an oscillating "tower" fan in my office - that way the air that does come out of the vent gets distributed.

Seems to be working well. We've abandoned using the Whole House fan for now - we are shut up tight as a drum to keep the heat out and the cool in. When we sleep at night we have an oscillating fan (actually the same fan I use in my office) that sweeps across us and keeps us cool.

It stays cool enough in my office that I'm quite comfortable and the family room (on the lowest non-basement level in the house) is almost cold.

The big question will be "how much will this cost?" but we won't know that until the Xcel bill comes early August. Last bill was $75 but that was for June when it was pretty cool and rainy. I'm willing to take a hit on the bill in exchange for comfort in the house - last Summer was brutal, I don't want to go through that again!

I just looked through my Xcel bills for the last 2 years (since we moved in here.) Winter's highest bill was $151, that was just for one month. I'm willing to go as high as that for a month or two in the Summer in exchange for comfort. Of course, the big difference between Summer and Winter bills is water - we have a yard and a sprinkler system so water bills can be as high as $75 or more a month when we water (May - Sep.)

It's too bad the wife is a green thumb who loves gardening. If it was just me I'd murder the grasss and replace it all with rock. No sprinkler system, no lawnmower, just a spray bottle of plant killer to keep my yard looking good!