If you're like me the word block in the blockquote's name may make you feel like it's the correct thing to use for things like poetry, letters, etc. But as Turtle91 points out, the blockquote has a cite attribute, so a blockquote is meant for quoting something from a larger work. If you read the w3c's definition for blockquote they're quite firm about it being only for quoting something, not just a general purpose block of text that's visually set off from the surrounding text. If it wouldn't make sense to use the cite attribute when you use a blockquote then you're likely semantically correct to instead use a div.
I made the switch to div when Jellby or TeX pointed out that using blockquote for general blocks of text is incorrect. This is when I came up with the idea of using two classes; e.g., <div class="block poem">.
Anyhow, I bring this up in case you'd prefer to be semantically correct with your html.