I would suggest BRD around level 55, seeing you have a prot pally you could potentially kill that place, there are a fuckload of quests todo there and it is by no means a waste of time, as for the others you might want to try them around 59-61 if you dont want to goto outlands straight away, DM-E is considered the easiest of most 60 instances, probably followeb by lbrs. But the others might be a gear check for you.