Said it before, I'll say it again. Make the home system, all optimal, with all planets - even moons, breatheable atmosphere. Cooler than a sphereworld.
I assume one could change hydrogen to oxygen, but what about "none" atmosphere planets? not talking about moons either. tho I suspect the same rule applies to those.
Atmos: none is treated just like any other atmosphere type, except that you can't have a no-atmosphere gas giant.