If you have the budget for it, do hardware cloth all the way up the side. If that's just too much, apron out a couple of feet of hardware cloth and go up the sides a few feet, to help deter predators. The idea is this stops things like raccoons from simply reaching in and tearing out a chicken, and to deter rodents from sneaking in at the edge of the perimeter or trying to dig in. Most predators can climb so if that's a huge fear it might be worth going up higher, but for my set up it seems just having it towards the bottom is enough (because if a bear shows up, I'm not running out there to confront it!)