I tried several different locations for the unit when suction cupped to the windshield, including near the rearview, and disliked all of them. Athought I might reconsider the arrangement if my current solution turns out to be bad in the long run...

My current solution (worked it out last night) is very unobtrusive in terms of mounting hardware, and uses one of the existing screws on the instrument cluster cowling as its mounting anchor. It worked out quite well for this morning's commute. Basically, the unit's screen sits at the top edge of my instrument cluster. It's just above the 1 o'clock position of my steering wheel, with just enough space between it and the wheel to allow comfortable hand-over turns without bumping. And it's close enough to my right hand when driving in 10-and-2 position that I can hit the touchscreen controls without taking my hand very far from the wheel at all. Line-of-sight-wise, it manages to be just visible above the wheel (maybe about 1cm is cut off of the lower left corner, but that's OK because that's a fairly large icon that doesn't need to be 100 percent visible to be readable), and sits just below the lower edge of my windshield. So I can actually look directly at it without taking my eyes very off the road. I can still see the car ahead of me in my vision even if I'm focusing directly on the thing. This works out well, because I would hate to get in an accident because of looking too far down at the GPS screen.

The bracket I'm mounting it with is not quite as pretty as I'd like it to be (but still prettier and more stealth than a suction cup mount), so I'll work on it some more and see what I come up with. Once I have it looking its best, I'll post some photos.