i guess i have some advice for metros as well.
tokyo metros are nice because you can use the elevator for your bags. just make sure you avoid rush hour times or you will never get on a train.
paris metros are the worst. if i hadn't had my girlfriend to carry some of my stuff i wouldn't have made it through all the turnstiles and stairs. avoid them if you can.
london metros fall inbetween tokyo and paris. as a stood before the turnstiles wondering how i was going to get through, a guy who worked there came up to me and asked if i wanted to use the door. he looked at my ticket and then let me through a door for wheelchairs. when i got off the train and had to carry my bags up some stairs, a girl stopped and asked me if i wanted some help. to sum up: the metros are set up decently to handle bags and my luck with friendly people made it very easy.