@heidi11576 what hasn't been shared is with GTW if you have a pregnant Sim, you can join them in the hospital to give birth. That is fun, and you get a birth certificate. And if you have a male sim that was abducted and impregnated, you can join him too and you get this cute alien baby crib and an alien birth certificate. With the Astronaut career you can go to Sixam the alien world. And with the Scientist career you can go to Sixam.
It is totally worth it.
I have played the scientist, but haven't got to level 10 yet. And started the Detective careers. But I haven't done the doctor yet. The children get a doctor kit (not sure if it is GTW or Parenthood that gives it to them. But by playing with it, I heard it makes them a better doctor as an adult. But I have yet to test that.
Also the bonus of having retail stores. You can create any you like, change the existing ones that come with the pack and just visit them with your sims to purchase stuff. You don't have to run them.