Okay, as everyone knows, I don't have a lot of expansion packs, but I've figured out a way, using what has been stated as acceptable, to not repeat 4X4 collections. Maybe this will help others. I'm using: beetles, butterflies, inventions, gems, plants, sculptures, spirits, wedding gifts, metals, fish, career rewards, lifetime rewards, paintings, potions (no value), celebrity gifts, and books. The only skill certificates I will use as career rewards are cooking, guitar, and charisma. And yes, I'm only going to let my politician learn charisma. As far as skill challenges go, just make sure you save them for one heir. For instance my heir #3 was an inventor, and although he reached level 10 in handiness, he didn't get any handiness skill challenges. I'm saving those for my astronaut. Same with heir #4, a firefighter, currently level 8 . The poor guy got Diabolical Detonator, Widget Wonder, and is at level 8 in bass (heading for Master Bassist). He just had his adult birthday.
I'm almost done with the first town and will report my stats soon.