I've always used "mundane" to mean not only worldly but with the suggestion of being ordinary, uninspired, common, simple, obvious. "Elegant" carries connotations of being special, high-class, somewhat out-of-the-way yet still appropriate, perceptive. Elegant can be simple too.

Select all that apply.

"Mondaine" as "elegantly world-wise" may place it among the faux-amis; in English "mundane" emphasizes the commonplace, rather than the loftiness of elegance. At least as I've used it. (Whom are you going to believe, me or some strange dictionary?)