Originally posted by Crayola
The awl is used for many things! Punching holes in leather or plastic is a common one. The hole is there because you can use the awl, along with some "thread", to do some rudimentary sewing. You won't make Cinderella's dress with it, but you can make some improvised clothing if needed (say, caught in the bush), etc. I actually used the awl on my SAK for a lot of scraping, poking, stape prying, and other odd jobs that the other tools don't do that well.
As far as which one to get, it is best to write down what you want the SAK to do and what tools you'll need, and then buy the model that fits that description. When I chose my SAK, some tools I picked because I wanted them just in case (saw), though I knew I might not need them much. Also, I chose it to go with mt heavy duty folder (Buck Strider tanto) or fixed blades that I carry. So think of what other gear you carry too when making your decision.