On the whole I was really really impressed with all of Woburn safari park. There wasn't a single enclosure I didn't like. I loved the lion enclosure which was several acres large and you actually have to search for the lions, it was almost as big as their natural territory size. The lions were the biggest enclosures by far but all of them were massive, all of which had lots of natural trees and bushes. I didn't notice the wolves wandering free around the same enclosure as the bears until they cam loping around the bushes for feeding time.
But my favorite was the squirrel monkey enclosure which was walk through. It was large and open with no roof, but well designed over hanging mesh sides to keep them in. This is a technique that's normally used to make the visitors feel better about the enclosure, it gives a more open feeling. But in this case this allowed the safari park to have naturally growing trees in the enclosure. It was brilliant, they were large and very good for the monkeys to climb. They also had little structures to climb on and ropes for them to walk along.
They also had access to an indoor area that was entered through half a dozen tubes, to get into it there were little flappy doors that the monkeys could open. I also loved that they had about 3 mothers with young infants clinging to their backs. it is probably the best enclosure i've seen in a while!!