I'm not saying every enclosure all the time - I'm saying a scattering of volunteers at busy times would do no harm and might make people interested enough to want to come back again and again. You get more out of what you see if you understand more of what you see.
I think you are 100% right! I visited London zoo last summer for the first time in well over 15 years and I wasn't overly impressed, to me it seemed to be a big kids playground with just a few animals thrown in.
For me I dont take much notice of the signs as I know in most cases what animal I'm looking at, and if not have a good idea what group it is in, then I will look just to be sure.
The idea of having a few folks around the zoo (or any zoo) is also simple common sense, I've seen it in action at Philadelphia zoo and let me tell you it really does work, so much so that it was my lasting impression of the zoo ( but maybe it was because the lady was just so good at her job)
I get the idea that you might be American by your style of writing (no offence if you are not!), but Americans know how there things work.
Now onto the website, again you are absouletly right. When I'm looking to go to a new zoo in a different country or another area of the UK my first port of call is the website, I look for how easy is it to find (and by public transport if outside the UK), the price, opening times, and what food is on offer, which is also important if you are away for more that half a day, but most importantly what animals are on display, if I cant see this on a website easily and in clear good detail I might very well decide to look elsewhere.
Can I ask you to look at Dudley zoo's site to see how they do it, just look on the news section and you will see how easily it can be done, with animal blogs ( written by the animlas themselves in some cases

).
Also their season ticket is less that half the price of London, so for sheer value for money I know in my mind which is best.