DIY Network Architecture for 50+ person co-working space?

Seconding a small Sonicwall. If it's mounted in the right place it should easily provide wireless to the whole place, and if not you can always get a sonicpoint. It will easily handle 50 people on the wireless with no issues. They have excellent QoS and are very capable when it comes to blocking or throttling specific traffic like torrenting. I'd also suggest if you're going to do the multiple APs with the same info setup, to actually have them setup like the sonicwall/sonicpoint type of pair, or at least with one as a repeater paired to the main one(via cable, obviously). Simply setting up two with the same AP name and password can cause irritating problems. Overall i'm with bobdow though, this all soudns fine.

Again, I'm self-taught, and have only set up a few smallish networks before, and our non-profit is pretty strapped for cash. Do I really need a patch panel, or can I just run cables from the switch to the wall jacks? Will a wireless AP be able to handle 25+ clients? Am I overlooking something crucial? A patch panel is best. The wire in the walls should be solid core, and the wire going into the switches should be stranded. You will have connection issues plugging solid core directly into a switch. Too much strain on the connections. And no, I don't think a single access point will be sufficient for 25 people trying to use the internet. Wireless is a shared medium and all of those people will cause excessive collisions. If you will be charging clients for these services, they will not be happy with this setup. I would encourage you to consult with someone who has experience with larger networks like this.

Some things to consider: What happens when your router, firewall or access switches die? If you can buy/configure equipment with high availability features that would be best, but if that isn't possible then you should at least have some hot spares available (preconfigured so you can just swap in the replacement unit quickly). 100 people is a lot of people sitting on their hands when the network does down. If you only have one, don't commit changes to the router during production hours, no matter how safe you feel about it. It's like don't drive drunk and wear a seatbelt and look both ways when crossing the street. Do not commit changes to your only router during production. For access switches, whatever you buy should support LACP trunking to connect to the router (which should also support LACP trunk). Otherwise you will have 50 clients on a 1 gigabit uplink. 16 port switches are limited usually in feature set, I would at least get a 24 port managed switch. HP Procurve or Dell Powerconnects are okay for this. Like the switches, your WAP's shouldn't be consumer type stuff. It's not going to work great under this kind of load. Make sure you allocate enough money for enterprise gear. Patch panel. Get a patch panel. And make sure you test every drop with a cable tester (not a laptop) to ensure full connectivity. Also you will need a small half rack for your gear, don't just put your stuff on a shelf or something. Finally, make sure your switch closet is properly ventilated. This is a safety thing because it's a fire hazard.

Tracert makes good points. If you are going to use cheap unmanaged switches for your access switches, at the very least wire up the network in a star kind of configuration rather than daisy chaining. Or buy one managed switch as your "top" switch and put each access switch into its own subnet and VLAN. It might be a good idea to consider placing each wireless client into its own subnet. Everyone in the same subnet could be a security issue.