Every flight out of California over the Sierra Nevadas offers great opportunities for aerial landscape shots. I've tried with teeny camera like the Canon S30, and monster cameras like the Canon 20D with various sizes of lenses. On a recent flight to Florida, the Canon S3 proved the champion in this type of situation.
By chance, I booked a right-side window side on every leg coming and going. (6C, 24C, etc.) That was a lucky break, because the flip-out viewscreen made it easy to shoot sideways to the right. It wouldn't have worked nearly as well on the left side. When an interesting landscape came into view up ahead, the best unobstructed shots came while shooting straight out to the right. I framed those shots comfortably by tilting the viewscreen at close to 90 degrees, so I could look straight ahead but still see the view to the right, downward, and sometimes even a little behind the plane.
The S3's 12x zoom was also very handy. Zooming in from a great height produced a bunch of interesting shots with abstract shapes of mountain ridges. The S3 goes from wide angle to full zoom with only a tiny extension of the lens -- seems like about 1 millimeter! Zooming with the 20D required a lot more room next to the window.