I really love the public domain. I would like to do more with public domain characters, but I have done a little bit here and there. Honestly, the public domain today is what copyright was supposed to be, really...it was only supposed to be a little while, long enough for the creator to get a little benefit from what was created, but not enough to sit on laurels for the rest of one's life. Of course, the public domain today still takes much longer than copyright originally took to allow others to do anything with a copyrighted character...it's a shame. We're stuck with a dysfunctional system that allows for far too long for any copyrighted character to stay in copyright, which means there's an effective monopoly on said character's development.
I did do a chapter based upon Pride and Prejudice when I was doing Incubus Tales, and that was so much fun. I really enjoyed playing with the interpretations of characters I'd read in a beloved novel (though my favorite Austen work is Mansfield Park); one day I'm sure I'll do more.
It's very exciting to think that every character in Shakespeare, for example, is public domain. One of the most iconic creators in the English language, and all of his works are at our disposal! It's just up to us to interpret them. How exciting is that?!