Just to add something that's bitten me in the past (and something you're probably already doing)...make absolutely SURE you have good, verified backups before doing a shutdown.
I have suffered at the hands of thermal shock twice. Hard drives that are up and spinning 24/7 for a long time, heat up, and naturally wear. A quick reboot is fine...but off for several hours, being moved, and brought into a cool new server room, can cause the drives to seize, and not come back up. We recovered once by heating an array with a hair-dryer, and things started working, but the other time, data was lost. Just FYI.