Network Design Wisdom

What are some tid-bits of wisdom or 1% improvement that makes all the different when it comes to network design that our community may have?

I’ll start with some examples,

1. Wireless APs and LAN for a single area shouldn’t terminate in the same IDF. So a floor or areas LAN runs back to IDF1 and the APs in the same area run to IDF2. Thus if an IDF is lost the clients in the area can still utilize the wireless or LAN infrastructure.

2. The lower or higher portion of your subnet that is excluded from your DHCP scope for a pool of static IPs should start and end on a bit boundary so policy may be applied on a firewall or ACL.

What does everyone else have?