Today I thought I'd give them some time in the harness and then leash them up to go outside. I brought one cat at a time for sanity's sake; Bella went first.
She sniffed every plant in the front yard, crouching low, rarely uttering a quiet yowl of confusion, but she started to enjoy the environment. She ducked behind some bushes and practiced crouching under cover. Then she trotted through an alley of leaves to the back yard. She's very familiar with gazing out the kitchen window and surveying the yard but now she was in the middle of the experience and really seemed to appreciate it. Then she started to freak out, running under bush branches and a drainpipe which resulted in the leash getting tangled, so I brought her inside.
Then it was Toki's turn. He had be staring at us with envy and some anxiety, watching Bella stalk about the yard. Toki started out only wanting to sniff the front steps, though, so I had to carry him to the front yard. At first he stood still, not knowing what to make of it, and then he was on familiar ground: a leaf fell and he darted to chase it. Any time a leaf rustled, he pounced on it with real glee. Then we started to trot up the sidewalk and it was Bella's turn to be jealous. She sat in the sunroom windows, staring at us with an expression of tremendous injustice, darting from window to window to gain a better view as we strolled. When Toki needed to wander into the street, I reeled him in and we went back inside for a debriefing.
I removed their harnesses when each came in and gave them treats, grooming them and praising them for their bravery. They seemed quite satisfied. As a souvenir, a leaf stuck to my boot and fell off in the living room and Toki had some pleasure in pushing it around.