I used to have my rabbits out all day and sometimes all night unsupervised- the walls were to high all around for foxes to jump over i think and i wasn't near any parks, it was a very built up area.
Here i have them in a 6ft pens, although they are unsupervised as i have high walls, they are penned in. Sometimes i let them out of the runs, but they are supervised when i do go outside the run, as one of the back walls is too low for me to feel comfortable letting them be unsupervised- one i get round to building that up, i will have them out free-range no doubt- My bunnys are big enough to fend off cats.
My cats co-exist peacefully and other cats are happy to lay next to the pens without trying to get them etc. The only thing that worrys me is that dogs can jump over the wall where i am now, i do take them in at a night now for this reason until the wall is built up again.