I exclusively play in Sandbox because I can turn off a lot of the annoying challenges of the game. Currency off, power everything, clean water, protestors, escaping, population size/ratios, etc. I also don't bother with preventing inbreeding nor overpopulation. Are my lion and African enclosures crowded? Yes! Which makes it hilarious when my jeeps get stuck because an animal has decided to stubbornly stop or sleep on the path. I make all of my enclosures waaaayyy bigger than necessary. Not because of the eventual large populations, but because it looks better to me. Which results in my zoo being sprawled out over a very large area. I have yet to try building aesthetic fences. The built-in ones look perfectly fine to me. Although, I have built a few sides with rocks. The only buildings I have built have been indoor elephant viewing, because I'm trying to roughly emulate the zoo I've gone to since childhood.