To get to Barcelona from Paris, I took an overnight train.
When I got on the train, three Canadian guys were my roommates for the night. When they walked around and checked tickets, they had the guys move to a different room because it was a female room. I got my own room. Awesome.
Sleeping was horrible. It was loud and bumpy. Not a good nights rest. But I got my own room, so it was okay.
Next time, I will fly. The flight from Paris to Barcelona cost the same as my train reservation. I value convenience a lot and this time I didn't think it through.