The Usage notes from dictionary.com cover this question remarkably well. Should anyplace be one word or two words? Is it formal or informal? etc.
The adverb anyplace is most often written as one word: Anyplace you look there are ruins. It occurs mainly in informal speech and only occasionally in writing. Anywhere is by far the more common form in formal speech and edited writing. The same holds true, respectively, of the adverbial pairs everyplace and everywhere; noplace and nowhere; and someplace and somewhere. The two-word noun phrases any place, every place, no place, and some place occur, however, in all contexts: We can build the house in any place we choose. There's no place like home.
To answer more specifically about your example "anyplace useful" - while that's understandable, another phrase might be preferred. "Useful" is not typically applied to restaurants.
"Let's find a place to eat."
"Is there anyplace useful within the campus?"
Is there anyplace good on campus?
Are there any good places on campus?
Do you know a place on campus?