What were your server room pain points, big wins and must haves?

What were your server room pain points, big wins and must haves?

Like many people on here I suspect, our server room has evolved over time.
At the beginning we had a single server running Microsoft Small Business
Server 2000 and it sat in the corner plugged in and happily did all our
emailing and firewalling.
Over time we have deployed a few more servers and they all sat on a shelf
until we took the leap to using a few rack mounted servers (why do we need
those when they are so expensive, asked the bean counters!) in a little
mini soundproofed cabinet.
Fast forward a few years and now we have 2 racks, with lots of storage,
switches, servers etc. and are about to move them all to a brand new rack
in the room and I was wondering if there are any words of wisdom e.g. do
we need to earth the rack? Opinion here is divided as some think that
simply by having PDUs screwed on to the rack, it is therefore earthed.
I know that proper full on server rooms will have all sorts of fancy stuff
like environmental monitoring, PDUs with power draw displays etc. and I'm
not looking for a "best practice" answer about how to run a datacentre as
that would be beyond the scope of serverfault.
However, I suspect there are quite a few sysadmins who's server rooms have
evolved and so I'd be interested to hear the main pain points people have
experienced and the "big win" and "must have" features and equipment.
My personal ones are
get cabinets 800mm wide rather than 600mm so you have space down the side
for cables
use cable management arms to avoid spaghetti wiring
colour coded network cables can be good to see things at a glance
get rid of side panels and front/rear doors unless you really need the
security
get a monitor/keyboard/mouse tray