I voted "whatever."
Just shove both of them into the Books/Manga forum, make threads for each individual VN and light novel.
e.g.
Light Novel: Kara no Kyoukai
VN: Katawa Shoujo
Most will get minimal discussion, like most manga series threads do. VNs are LONG (so are some light novels), and take some dedication to finish. If people don't already have the wherewithal to play/read them, they're not about to start just because we add a section.
Frankly, the biggest problem is that it is impossible to discuss the content of either of them. No one can discuss VN details until everyone has finished them, because it's so easy to spoil the big plot twists (if they have them at all). Light novels are just as bad, since they are translated at varying paces, and you've either been reading it for months, or are just starting, like any other kind of novel.
The most discussion that either format can really get is something like, "This VN/light-novel was very entertaining. I enjoyed ____ the most, but I can't really go into details without spoiling."
edit: I guess I should have voted "bad idea, kill it with fire" given the way the question is asked.