Are there any examples of elegant CL code that performs lots of vector geometry calculations? I'm skeptical that this sort of code would come out elegantly in CL (at least if it had to perform reasonably well).
This isn't a direct answer to your question (it's not a computational geometry codebase), but one option for
implementing geometry might be to use MAGICL. [1] It is optionally and transparently accelerated by BLAS/LAPACK.