Here's the details for the network we set up for Super Happy Dev House Singapore May 2011 which supported 200+ laptops + phones.

All the wireless devices were set to their lowest power output, with SSID SHDH for 2.4 GHz and SHDH-5G for 5 GHz.

Should the wireless have failed, we had ~90 wired ports available. All the NAT / DHCP (30 minute leases) work was done by the apple. With a bigger venue, the ~250 IP limit of the apple means we'll have to use a different NAT box.

Update: 2011-06-30
It was an airport extreme, not an express that served DHCP.

Wired Network:
Zhone ADSL - Apple Airport Extreme - [ D-Link 10/100 Switch "A" , 3 x Colubris MAP-320 ]

D-Link 10/100 Switch "A" - [ 1 x cisco AIR-AP1252AG, 1 D-Link 10/100 Switch ]



2.4GHz Channels
===============
cisco 1
colubris 3
colubris 6
colubris 11
apple 13

two rooms together =~ 10m x 25m
+----------------------------------------------------+
|                                      
|                colubris               cisco
|                d-link                 d-link
|          
|colubris
+        +----------------------------------+
|
|
|colubris
|apple 
|zhone
+----------------------------------------------------+