My commendation checklist for dungeons:

Was everybody good? If yes, commend DPS.
Was the tank bad but the healer good? If yes, commend healer.
Was the healer bad but the tank good? If yes, commend tank.
Was the healer and tank bad but the DPS good? If yes, commend DPS.
Was everybody bad? If yes, leave and don't commend.


My commendation checklist for trials/raids:

Was everybody good? If yes, pick based on tiny things you noticed that you liked that they did.
Was somebody a BLM/SAM/DRG and didn't die? If yes, commend.
Was a healer bad? If yes, commend other healer.
Were both healers bad? If yes, commend tanks.
Was a tank bad? If yes, commend other tank.
Were both tanks bad? If yes, commend healers.
Were tanks and healers bad? If yes, commend DPS.
Were one/more DPS bad? If yes, commend good DPS.
Were all DPS bad? Commend tanks/healers.
Was everybody bad? Leave, do not commend, take a cold shower, try not to cry, cry a lot.