Mostly for inspiration! There are quilts at these shows that will burn into your memory forever because they are so fabulous.
One other valuable lesson I've learned after attending numerous shows relates to notions and gadgets. Watching countless demonstrations, you realize that while there may be a tool, ruler or gadget for every quilting task out there, the reality is that you will probably only end up using a small handful of what's available. This translates into more money in your pocket for fabric!