Shelley's To a Skylark, for example, is also a very famous work of its kind, more famous than this week's theme, but it too would be 'niche'. Ozymandias, on the other hand, would not be 'niche' because it is widely taught in schools. Similarly, a selection of Shelley's poems, would make a broader theme.
It's also unusual to have to refer to a single line in a work, where the line is not reasonably common knowledge (as an online search will confirm). It's not exactly: 'Hail to thee, blithe spirit...'