Cook the orzo according to package directions, omitting salt and fat. Drain; rinse with cold water. Combine orzo, spinach, and next 5 ingredients (through salt) in a large bowl.
Drain artichokes, reserving marinade. Coarsely chop artichokes, and add artichokes, reserved marinade, and 1/2 cup feta cheese to orzo mixture, tossing gently to coat. Sprinkle each serving with remaining feta cheese.