I think the best dating sims are the ones that have a larger and hopefully more philosophical plot goal which runs parallel to the courtship goal. In Harvest Moon you rehabilitate a decrepit farm into a farming empire, and some editions of the game add a secondary element like saving the town from real estate developers. In Azure Dreams you likewise rehabilitate a decrepit town. In True Love you have to balance your monetary, academic, and athletic achievements. In both cases this includes subgoals of solving NPCs' psychological and other problems. Other dating sims have been based around solving a mystery, or the more typical hero plot of defeating a villain and/or invading army (FF7 was initially designed to be part dating-sim but most of the design was canceled in development).