If you do not have a designed-in niche but do have a sizable wander-in shower, look at hanging floating shelves over the shower wall, like this spacious bathroom from Louis Duncan-He Designs. Snagged a sizable-scale storage cabinet (bonus details if it's vintage) but not particularly sure wherever to put it? https://juliusiuchv.targetblogs.com/31992646/5-simple-statements-about-bathroom-storage-cabinet-sink-explained