GW, it heavily depends on the version you play. In DA, okay, but in TA you'll notice their influence is so nerfed that their zone of influence is pushed away by any other race. One of the many errors in TA. They can colonize low PQ planets in foreign terrain (and their 100% loyality usually assures that these don't flip) but their SA won't come into play at these planets. Only at their core worlds, but just having a Superbreeder aside and you won't see much Yor-space at all... That could have been done better, imagine a spot in your empire where constantly ships are stuck at with speed 3....hehe
But generally speaking, if you wanna go for influence there's only the option to either mine-out the resources, and/or built an influencer base directly at a planet and max it out. With just a basic base here (in the middle of nowhere) or there, the constructor/cost for the base is nothing but a waste, esp. for a race made for warfighting.