probably the most important thing in photographing thru windows is getting the camera close to the glass with a nice large rubber lens hood and having the window in shade - if the sun is shining on the window, forget it
if your double pane windows are coated, this may be an additional problem
thanks for the reference to Window Seat. my experience with photographing from commercial flights is - a) plan ahead and get on the correct side of the plane for backlight and subjects of interest (for example - from Bhutan to Nepal in the morning you want the right side of the plane) sometimes you can figure out the routes from the map, but i'd love to hear of any resources for particular routes, b) with the camera up to the window, you can get decent images thru really nasty looking windows so long as you're shooting RAW and processing in LR, etc.
sometimes you're luck - recently flew from SFO to Albuquerque on the left side in afternoon, pilot said best views of Grand Canyon he'd ever seen, i thought the little windows on the United shuttle were incredibly scratched, but my wife urged me to shoot. 5d2 and 24-105, minimal dynamic range, but when you're focussing at infinity the window filter isn't too bad and Lightroom pulled some vary nice images from the limitedl dynamic range.
