What features can I add to my stream to make it more interesting?

Consider plants first, along the edges of the stream, to make it seem more natural. Reeds, grasses and ferns make good choices. If you have the skills and resources, adding a little foot bridge over the stream can be a quaint and pretty touch. Kids will enjoy stepping stones across the little stream, which can be made from large smooth rocks or even pavers, depending on the depth of the stream and its appearance. Some people even add moving features like a water mill, model boats or a fountain. It's really up to your imagination and budget but ask the kids or family what they'd like added too.