It can be tough with live plants, you end up with lots of the same types of low light loving plants that thrive or you have to do some rotation when they start deteriorating but it is definately worth it. To be honest of all the zoos and wildlife parks I've been to in this country, displays always used live plants (not that I've been to them all).
Chester is definately one of the good zoos and is certainly one of the larger ones over here. My only gripe is that they look to be going the 'modern' way of ordering the collection by keeping animals from the same "region" in the same areas. I prefer a more traditional, heres your herp house you know where they all were. An example would be having a random gaboon viper exhibit in the okapi/giraffe house. Just made it hard for me to find the animals I'm interested in, and I cant be sure I didn't miss something I would have wanted to see. But yeah, the displays were nice... they look to be very into their rhinos and hornbills in a big way.