@Clarys You're welcome. There are quite a few shoujo novels in the 'Licensing Suggestions!' forum, which are really good. I hope, that JNC will license them someday. In fact, they recently released a hint, which could be one of them.^^
Didn't catch this thread the last time through, but don't really get a chance to scan the forums as much as I'd like. On this, I'd have to say something of a variation from the story. I don't want it to be a spoiler, but it's nice if it can at least fit current events. Having said that, most of the images which have a lasting effect on me from light novels are those which are used for character introductions/additions. As I'm reading, I like having at least a face to attach to who I'm reading about. Especially in stories like Rokujouma, where there are an infinite number of characters, or Smartphone, where the wives-to-be and their families to keep track of, having a visualization of new characters in the opening art are probably those which I most appreciate. In volumes which include these, I tend to check them several times.