Interesting benjiboy, I had the same with my Polar Bears, guests would quite frequently end up in the exhibit and the poor bear was put in a crate. I finally noticed an enrichment object (the car tire) that looked like it was on top of the fence I removed the tire and it seems like it fixed the problem.
Some hints of mine (In random order):
Quick animals can sprint through the jeep gates, grrrrr.
Avoid jeeps going through tortoise exhibits, takes forever for a tortoise to cross the road.
In challenge mode I've often grouped 4 exhibits together, then created an empty no-mans land (2x2 squares) in the middle with a gate to each of the exhibits and a bench, then 1 or 2 keepers can handle those 4 exhibits without ever wandering off. (no gates to the outside world of cause)
Maintanance workers seems to only like the standard bench, make sure one is availeble close to your food court.
Theme your areas as much as posible, the food stalls cost the same, but requires no research and seems to be liked more by the guests.
Guests can see 10 squares, so don't use deeper exhibits, use the visible area view often to ensure your guests can see something interesting.
Most shelters seems to be affected by a bug where animals are relocated to the back of the shelter, so never place a shelter next to a fence, 2 squares away is best, same might be true for some enrichment objects.
Animals that can climb some fences can also climb trees, so don't place trees next to your safe fence.
The discovery kiosk (ES) is well worth it's price, place several near interesting exhibits and have donation boxes close by.
Don't forget to release animals to the wild, helps to build up your zoo rating.
Check your guests favourite animal (sort the guest list by animal, most popular will be at the top) and try and exhibit the top ones (often Koala, F. Fox, Meerkat and Flaminco)
Placing restrooms, benches and ATM's at regular intervals are obvious, but also add zoo maps, statues, fountains and playground equipment regulary.
If many guests are in need of something check where they are, if the problem appears in a specific area you should fix it fast.
Steve Irwin once said the most importaint thing in a Zoo are the animals, don't forget that. Healthy and happy animals are the key to everything as they make guests happy (better rating) and happy guests donate more money.
You can set up a special exhibit for photo challenge requirements, so if you need to take a picture of a red panda resting in a tree simply move a panda to your special area, add a tree (and no other places to rest) and click. Same for pictures with specific object, only place that special enrichment object with the animal.