You could consider doing it in a nice park like Bowen Park. Its is quite central to the city (fair for everyone to travel to) and has plenty of room. It is grass so you can do heavy falls and noone will get hurt. There is a large gazebo for people who want a wooden floor and concrete paths if you want concrete. Its free. I also find it gets you out of the 'dojo' mode and makes you feel a little more real. Plus you might find that the small amount of public exposure is actually good, as people will come up and say 'what is this?' and you can invite them to join in. I will put it to a couple of my mates to get them to come along.

 

L8rs.