This has probably already been mentioned in this thread, but one of my biggest peeves with the game has to do with pathing priorities, finding alternative seating, etc.
I recently had a Sim out running errands on the other side of town, and was queued to eat leftovers after completing the errands. I sent another Sim to eat leftovers, and that Sim stood by the fridge for awhile, and then went off to do something else - because the Sim that was across town apparently had pathing priority. A similar thing happens if I order a Sim in another part of the house to eat leftovers - instead of walking toward the fridge, they will stand there and wait until another Sim is finished at the fridge before they will begin walking to it. It's pretty hard to do family mealtime, because by the time the last Sim gets to the food, the first ones have finished eating.
Birthday parties are pretty chaotic, too. Even though I have beaucoup seating, I invariably have multiple Sims all planning to sit on the same seat, devolving into an "I can't get there" dance party and most of the cake ends up on the floor. It would be nice if a Sim looking for a place to eat would go sit somewhere else if his/her first choice is taken.
I'm sure the pathing algorithm is incredibly complex. It's great that, for example, a Sim standing in front of the dishwasher will move out of the way when another Sim wants to use it. Still, there is a lot of room for improvement.
Meanwhile, I guess we can laugh at those silly Sims.
