Piece of music similar in difficulty to the 1st movement of Moonlight Sonata?

I've only just been playing for a year and I just learned the first movement to Moonlight Sonata by Beethoven. It came fairly easy to me, and I wanted to learn another piece before going to the second movement. What are some pieces that are similar in difficulty to the 1st movement of moonlight sonata, whether it be the same or a bit harder. Also I have musical experience in multiple other instruments so theory isn't much of an issue, just technical demands give me trouble.