The 3 kinds I have seen are the inflatable kind, the rolled kind, and the folded kind. I'm curious what you guys use now. Or are they for different situations? The folded is really really light and seams like it wouldnt take much space if you strap it to the outside of a pack. The inflatable kind sound the most comfortable though.

There have been lots of discussions on this if you look back through this forum. I use a 3/4 length thermarest on almost all trips, and then add a full length ridgerest (rolled foam pad) for cold weather trips.