Look at
www.infinitywindows.com (I think I got that right). They're made by Marvin. It's actually fiberglass windows, but one interior option is wood grained. You use a gel stain to stain it any color you want. As replacement windows, most force you to lose glass area...these won't, of if they do, it will be much less. Very stable, same expansion rate as the glass, so the seals generate less stress, so they last longer. For areas you want to paint (say maybe in the bathroom), you could get it with the white gell coat instead of the woodgrain.
Vinal expands and contracts huge amounts with temperature changes. The UV inhibitors are good, but aluminum coated with something like Kynar would last longer and be paintable if you decided to change colors. Vinal can sometimes be painted, but often doesn't work well.
