The newest attraction at the San Diego Wild Animal Park is a 2 hour mule ride. Don't expect to ride amongst the antelope - this trip goes into the undeveloped backcountry of the park. Half of the park's acreage is marked for permanent protection as natural California habitat - a very worthwhile (and often unreported) aspect of the Park's work.
Here's a link: Wilderness Ridge Mule Ride
Here's a link: Wilderness Ridge Mule Ride