If you like science fiction -- especially the kind that involves space battles -- then you will most likely enjoy this Gizmodo article by Joseph Shoer.
So, I think the small fighter craft would be nearly spherical, with a single main engine and a few guns or missiles facing generally forward. They would have gyroscopes and fuel tanks in their shielded centers. It would make sense to build their outer hulls in a faceted manner, to reduce their radar cross-section. Basically, picture a bigger, armored version of the lunar module. The larger warships would also probably be nearly spherical, with a small cluster of main engines facing generally backward and a few smaller engines facing forward or sideways for maneuvering. Cannons, lasers, and missile ports would face outward in many directions. On a large enough space cruiser, it would even be a good idea to put docking ports for the small fighters, so that the fighters don't have to carry as many consumables on board.
I think it's time to sketch some pictures and write some stories!
(Hat tip: The Volokh Conspiracy)