re: Frankfurt Christmas Market

Euro trains are not like flying on a plane, not really close. You can walk around as much as you want, less people on them usually, and there are usually at least one restaurant/ bar car. The sights are often times really nice too, it's not like you are on an airplane high up. Obviously it's best to travel long distance to make best use of your time but I wouldn't sweat a 3 hour train ride much as far as discomfort.