I'd do them all in highly optimised x86 Asm, just because I can. ;-)
Not all students start at the same level; making the choice of language a free-for-all is just going to stretch that disparity even more. The ones at the top will naturally find ways to entertain themselves more, and the ones at the bottom will have no less idea of how to do things than copy-pasting code they found somewhere else (if the language doesn't matter, it makes that even easier...)
We were writing an interpreter using C++ which I'd rather have done in some Lisp-like languages.
On the other hand, I believe that doing something in an "unconventional" language for it is one way of improving your skills since you have to then apply true creativity and knowledge instead of just following an existing solution. Using a language which makes the task easy or even trivial doesn't really benefit the learning process.
