We tried the train station last year but abandoned our spot when we realized that we couldn't hear the music for Spectro very well. I think it might be a good spot if you can are right along the railing but if you are under the roof, the noise from everyone else up there with you is amplified. We went down and stood in the area around the flagpole which was an excellent spot to see both. One night, we tried sitting in our "usual" spot by the Castle but like msmouse said, it was too close to really experience all the effects of Wishes.
We go during early June and we always stake out our spot for Spectro and Wishes at least two hours before...