Yesterday, I proposed to synonymise graphic-novel and comics (just like that, without consulting anyone). Afterwards, it's been pointed out to me that collecting the two may not be the best idea, since clearly graphic novels (whatever they are defined as) are somehow different from other comics.
This is not a discussion on what is a graphic novel and what is not. Let's leave that for the main site. My concern is that of practicality and usage in general.
The tag will have to have a usage guidance to be applied consistently. What would the usage guidance say (i.e. where do we draw the line between comics and graphic novels)?
Some works have been named "graphic novels" almost unanimously by readers and critics. Others - not so much. What one considers a graphic novel - others may not (e.g. I call Sunstone a graphic novel, but I haven't heard of other who do so, mainly because it was originally a webcomic).
"Attracting experts" - the lists of "top-100 graphic novels" are all pretty much the same, typically starring some or all of the following novels on top: Watchmen, V for Vendetta, The Sandman, Saga, Maus, The Killing Joke, The Dark Knight Returns.
My point is, when one hears "graphic novels", one expects a certain list of works that have been branded as graphic novels by countless readers and critics. From that perspective, there may be people who only read comics that are graphic novels, and this tag may prove useful to them, especially given that all the comics questions on this Stack so far have been about graphic novels.
Ergonomics - will graphic-novels make search easier? I guess it will, because sometimes people forget to mention that the work in question is a graphic novel (guilty!).
On the other hand, will it be used with comics or completely separately? If the former, we have the problem of the tag count - maximum 5.
author tag + title tag + comics + graphic novelmakes 4, which leaves only 1 tag for symbolism or plot or whatever. And what if the question asks to compare two works? Too many tags.
Those are some of the aspects that I think should be taken into consideration when deciding the course of action.
I see three possible solutions: