I like the lion enclosure really, as Pertinax says a few more plants might make it look a bit more exciting, but I think that'd be more for the benefit of the people than the animals. Beats others I have seen (Bristol, London, Twycross), not sure whether it's better than Edinburgh's.
I'm not quite as fond of the tiger enclosure, but come to think of it I always look at tiger enclosures and wish there was a bit more to them. There's far smaller tiger enclosures in other zoos, and the lush planting is nice- I do think it would be better in only viewed from one side. I think it's just that part of me thinks, that for a zoo with a reputation like Chester it'd be brilliant to see a 'world class' tiger exhibit with the whole immersive jungle feel. I'm sure it'll happen in time.