Anthony,
You can use your le crueset griddle to cook steaks, sausages, fish, anything you desire grill marks on. You could even do panini.

Assuming your griddle is a genuine le crueset product, it should perform very well because it is enameled cast iron. It will heat up and retain heat better than many other materials, so it will offer a good sear. You just have to be brave enough to let it get good and hot.

Be sure to try it out soon!