I made a large cube primitive to serve as the ground for a small town model I'm making. I want the ground to be tiled like a cobblestone pattern, but I also want to make a small border along the perimeter of the ground where the cobblestones meet walls and such. Do I do these borders with seperate planes and seperate textures? Or do I make a large texture with the border art awready in place to fit the buildings over?
Or what do I do?
It really depends on the quality and purpose that you're going for. You can take the flat approach as you have done, but keep in mind that you're giving up the advantages of working in 3d, especially depth sorting. Objects won't appear to block objects that should be behind them, so the method (in my judgment) is impractical for anything but still, overhead shots.
That said, you can get great results simply by finding a picture of the ground as you would like it to look and applying it to your ground plane. Yes, one large texture, and if you're using any procedural textures, output them to a file. Just remember that it will tend to look right only from the angle at which the picture is taken and any modifications you want to make will have to be made in 2d (e.g. photoshop).
If you want to be able to animate your camera or to take shots from low angles, it's quite another story. You should make 3d models of as many surface details as you can, especially if they are close to the camera.
Hope this helps. Maybe it was only part of your question.