Perhaps I am alone in this, but I and my friend played about 10 matches between the two of us this weekend and we found that colonizable planets tend to be clumped together in sections in the galaxy (specifically on the spiral map) with some players getting lots of colonizable planets (10 planets in 10 systems) and the others getting lots of uninhabitable ones (I'm talking traveling through 20 star systems in a 'sector' and not finding a colonizable planet).
Feel free to add or comment.