jdavis, as a GSD owner, I know exactly how intelligent the breed can be. With that said, it's neither easy, nor difficult to train a dog and like many have already said; hitting the dog will not in any way help resolve your problems.
http://www.dogproblems.com/ try visiting that site for some very insightful help in training your dog. The guy who runs it, Adam Katz (I found that a strange name for a "dog" trainer), definately knows his stuff. He's god a great book as well as a forum where other dog handlers/trainers give great advice. Give it a shot.
I hope you persevere with the dog, they honestly are beautiful animals.
Cheers ...