One thing about Cores... they are abusable. I always liked abusing them.

Scenario: You signed naps with everyone even remotely near and you included cores. Explore your core LAST! Dont put bankers in systems with others neccessarily but if there is an empty system outside the core that is safe.... FILL IT FIRST! You can effectivelydouble the size of your acting core via this method.

Second... plan fun times. Napped with two fueding fams? Explore a system between them, only take 7 planets. Put your DS there. Oh snap... watch them hate clearing thatsystem but NEED to.... oh the fun in killing massive flets and not being in danger yourself.

Next... plan extra cores. Not nap type but effective secondary cores.First thing on day 4 have four attackers send to a system far from anyone. Laser and portal when they arrive. They explore the area and all people send fleets to capture one planet.

Now 25% of your exploration happens there and attackers plan defense of it and your main core. It works real well on isolating threats to all your planets, giving you better reach, and in DS games. I once had 4 cores set up successfully. Fun times that.

Finally... forthe sake of sanity...find all bonus planets in your core, all of them, and organize them into segments... early expo, mid expo, end game expo... and assign people planets so no one grabs them. Seeing a banker on a 45% Iron Bonus is just wasteful.