Two modifications that I found worked for me: First, increase the oatmeal (make sure it is very finely ground) to 1 cup - this produces a thicker and chewier cookie. Also, try dark chocolate chips or chunks - they add a level of intensity to the recipe.
The first time I made these, I read the recipe wrong (1 cup oatmeal) and they were awesome - thick, chewy and a great texture. The second time, I made them as printed, and I found them to be flat and crunchy - still tasted great, but not the style of cookies my family prefers.
One thing I'd like to try next time - half of my family likes cranberries, so I may try half of the batch with a handful of craisins added to the end (in addition to the dark chocolate chips). Even raisins might be good.