I agree, their planet system is laid out nice, but for the next Sins I'd enjoy seeing the phase lanes between planets change over time, and randomly reconnect to the closest planet/s as they orbit around a sun.
Granted planets orbiting that fast isn't really realistic, but then again neither are alien Vasari or psychic Advent, but they makes for a heck of a fun game none the less 
Having the moons of planets (which orbit the planets) places you can build a garrison defense fortress on would be fun too, sort of like a huge hangar bay/gun turret combo that held a dozen fighters and 4-6 long range weapon systems or something.