I usually carry a spotting scope and I use it on a window mount on my truck for glassing distant ridges and valleys. I don't take it with me when I'm on a stalk though. I carry a pair of Leica 10x42's or an ultra-lite pair of Nikon 10x25's when I'm actually hunting.

Spotting scopes are a handy tool but their bulk limits the way I can use them since I tend to hunt light and on foot.