"One of the best things you can do in this world is take a nap in the woods." ~ Jayber Crow by Wendell Berry
"While it may be a lot of work, the view is best from the summit." ~ an anonymous staff member of Philmont Scout Ranch
Enjoy the day
Yes, the 72 refers to the width. I am a big guy (6'5", 250 lb) so I went with an 11'x6' (one of the two standard sizes at the time).
Length really helps with getting a flat lay - moreso than width, I think - but width helps as well. If I were to get another one now, I might reduce the width a few inches, but not all the way to 60.
The width does help with expanding the possible sleeping positions (side, stomach, fetal). I don't have any problems getting my UQ (HG Incubator) to stay underneath me no matter how diagonal I am. But I don't fidget that much while I sleep, so I've never had an experience like ^shane^.