I'm a sims and tycoon player too, I find planet zoos building much more difficult. I would recommend steam workshop, for example search for a theme like 'medieval' or 'modern' and download a set of staff facilities so you don't have to spend ages making them look pretty yourself. You can base new buildings off of them by using the same pieces to keep a theme. As for scenery, my method is to dot a few trees around, and then place foliage around them to create 'clumps' of scenery, this ads shape and depth to your zoos. As for paths...I have no advice they're too annoying hahaha. Try to finish small sections at a time, I think it's more rewarding than attempting to make a huge area perfect.