Jim,
I have one of the older blue Coghlan's Thermal Blankets that has seen 3 fire seasons of use and is still in fairly good shape. I usually use it for a ground cloth for my sleeping bag, but I have also spent several nights in it. They are definatly better than a space blanket or even an AMK heatsheet.
Mine measures 11"x6.5"x1" when folded.
Kevin