Helpful Hints for Happy Zoo Tycoon Guests at The Zoo Enclave

Guests enter the grounds with a happiness rating of 75. Place a large fountain and some nice shrubberies (or other foliage) at the front entrance to give your visitors an immediate happy-boost. Also be sure to include a restaurant, bathroom, rest area, and exhibit in the immediate vicinity.
Watch your prices inside the zoo! While guests will pay $25-29 to enter without too much grumbling, high food, drink, attraction and gift prices will make them very unhappy. If you've recently raised prices and seen happiness plummet, try resetting them a bit lower.
All guests are animal activists to some extent. Unhappy / poorly treated animals will make guests angry.
The more happy exhibits you have, the happier your guests are. Arrange your zoo so guests are always in sight of at least one exhibit.
Every guest has a favorite animal. Seeing this animal in your zoo increases his/her happiness. A wide variety of animals targets the most guests, but you can view a specific guest's favorite by opening their dialog box and clicking on the Heart icon.
Use the cobblestone, brick, gold or boardwalk paths. These have higher aesthetic values and increase happiness.
Keep paths wide, at least two tiles, and wider for very high traffic areas.
Make redundant paths: always offer multiple routes to every section of your zoo.
Pretty it up; guests prefer an attractive zoo with lots of trees, flowers, statuary and other aesthetic enhancements. Check the Aesthetic Happiness Charts to see which items please guests the most. Don't forget to provide plenty of places for them to rest and take in the views.
Use appropriate premium fencing for your enclosures. Guests know and appreciate quality building, and will be unhappy with shoddy materials and/or maintenance.
Hire at least a couple of tour guides.
If you have food stands and trashcans, hire at least one maintenance worker for every 50-100 guests. As the zoo grows, assign some to strictly maintain fences and others to strictly deal with trash (about 40/40), with the remaining workers left to roam where needed. If you stick with restaurants, you can place fewer trashcans and subsequently hire fewer maintenance workers, but you still want to maintain a ratio of 1 worker to every 200-300 guests, as well as enough to maintain your exhibit fencing. This would mean assigning maintenance tasks at about 60/40 or 70/30 fencing/trash.
Keep your exhibits close together. Guests hate having to walk more than a few tiles in order to view an exhibit.
Guest viewing area: guests must be within 2 tiles of an exhibit to see it, and then they can see about 10 tiles in. If they don't see any animals within this area they start to get mad, so watch your exhibit depth.
Try putting watering holes at the edges of exhibits, with shelters toward the middle or back. This encourages animals to come out into guest view, while also allowing them some privacy when they need it.
Guests enjoy a good combined exhibit.
Guests don't like trashcans. They're a necessary evil, but try to limit their placement to strategic locations.
Aquatic attractions (Swim with Dolphins, Swim Shack) make guests very tired. Locate these near lots of seating and a good restaurant.
Guests go crazy over marine shows, and forget to eat, drink or relieve themselves. Guests exiting shows will need to do all of the above, and quickly, so be sure to place restaurants or food / restroom courts just outside the show area.
Check guest thoughts about exhibits when they're passing by. All exhibits should register some thoughts - if the guest isn't thinking about animals as he's passing them, then he may not be able to see them. Consider adjusting exhibit sizes or configurations to increase guest viewability.