@Vhampton, thanks for the tip. I figured out the problem. I had started with the normal plywood texture, and not the Plywood-hrz.jpg The Plywood hrz has a pattern to it already, and when it's scaled, allows you to make the desired look. I will say that I do find it kind of frustrating that there isn't a way of tiling any texture with a grout line. The texture pattern overrides anything that you try and set up with the material... kind of annoying.
@jcaffee, I appreciate the feedback, and I'm definitely looking to learn more about the Wall Material Region. But I'm not sure how that tool allows you to create the seams on a repeating pattern. Do you combine it with another tool to get the pattern to repeat? The picture you attached earlier looks great, BTW.
Thanks,
Nick