Tomorrowland is about the worst place to be (blockage of the buildings is pretty bad.)
If you were riding Astro Orbiter, that would be pretty cool.
But, that ride is so short and difficult to time, there's little chance to actually do that.
If you are in Tomorrowland, head to the bridge entrance to Tomorrowland coming from the Hub (near Stitch building) from where you can see the side of the castle.