You should run what your tire, temperature, load, and road conditions dictate. For me, I have run as low as 20psi in my snow tires and as high as 40psi in a set of Pilot Sport 4S when they were all heated up running canyons. Tire pressure should be adjusted for towing and for temperature and your starting point will be dependent upon the manufacturer of your tire and what they recommend. For example, I have found with Contis that they love to run at much higher psi than the sidewall recommends. That is the real answer.
The set it and forget it answer? For "MOST" street tires load rated for our vehicles, keep em at 35psi all the time and you should be fine. If you notice uneven wear, increase or decrease pressure to compensate appropriately.