Hmm good point about the mail. Perhaps just never letting the toddlers have them would be enough?
Another thing to remember - field trips sometimes give skills, which can be a pain when you're trying to land opportunities for other skills.
If you have trouble with snow days reducing your kids' performance at school (or rather, not allowing them to improve it without tutoring), get the weather machine LTR thing. The night before, set the weather to sunny. If it starts snowing any time in between then, set it to sunny again, and you should be ok most of the time for school the next day.
If you care about your immortals happiness, give them the insane trait if you plan on locking them up alone, so they can talk to themselves, and the hates the outdoors trait so that they don't go stir crazy.
Don't lock all of them up together with spouses. I had gen 1 and gen 2 with gen 2's spouse in together, and gen 1 STOLE gen 2's spouse! I didn't think that it would be possible. Right up until I failed I kept getting messages about her being faithful to him, too! As well as plenty of cheating messages, which was totally weird. After he died, mother and daughter finally reconciled.