Ultimately how a poem or story in verse is formatted will depend on the publisher but when I send out poems that rhyme I usually write them in stanzas as that is the format that suits my type of poetry. The best advice that I can give is that whatever you choose to do, be consistent (within the one poem or story). Writing in rhyme and rhythm lends itself to pattern and it also makes it easier for the reader to read. I also double space my work when I send it out as it allows the editor or publisher to write notes on the manuscript if they need too.