I'm up in Bendigo, so all your 'burb LANs aren't really a choice. Except for epic ones. Such as respawn. Then it's worth going down.
We have two main ones going at the moment.
The private one myself and another guy run (Most we've had is 45, average 35ish) with the help of quite a few contributors.
BLAM is a revived LAN (it's being run by a guy I know, not the guys that used to run it though). It's last LAN (#4) had 40ish too. It's open to the public. Quite a good LAN. Small LAN, so we can get away with unmanaged gigabit (when the cables don't fall out), and we.. err.. learnt a little about the circuit layout in the hall we'll be using too. Let's just say they were kind enough to not provide us with a circuit diagram, and nobody thought to check out circuits before the LAN got going (not my fault. I wasn't there until later in to the first day

)
There's another week long private LAN that happens yearly, with weekenders throughout the year. It's a house LAN though. So hot, cramped, etc. I've never been able to get to a week long one, but the weekenders are epic.