Those are some of my favorites too - Milton mostly. I study Milton pretty intensely. I've read nearly everything he's written (except the stuff in languages I can't read) and he's one of my all time favorites. Have you ever heard of Stanley Fish? I'm sure you have, but he wrote a couple beautiful books on Paradise Lost. He covers all sorts of stuff, including Satan's rhetoric. They're wonderful, and I would definitely suggest them.
Coleridge is fantastic, and Rime of the Ancient Mariner is just amazing. He's not my favorite Romantic (that title is a toss-up between Keats, Byron, and Shelley [Percy, not Mary]) but he sure did some wicked good work.
I'm actually re-reading (and finishing what I didn't read) Le Morte d'Arthur right now (a character in a story I'm writing is really into Arthurian legend). It's still fascinating.
As far as dystopia/utopia type literature goes, Brave New World is always great, as are the other classics (1984, Fahrenheit 451, Lord of the Flies, etc.) but one of my favorites is Margaret Atwood's The Handmaid's Tale. It's wonderful. I'm also a big fan of Takami's Battle Royale.
I got into that stuff in high school, but didn't really enjoy it much until I started studying older stuff (Moore's Utopia, Plato's Republic, Butler's Erewhon). Once I started reading and studying the roots I found a new appreciation for the utopia/dystopia.