I believe it is very common that people need the whole vim feature-set. So, I'd suggest that having a version of vim package, so to speak 'vim-huge', built by (at least) following flags would be useful:

--enable-pythoninterp # Python interpreter, required for very-popular pathogen plugin
--with-features=huge
--enable-multibyte

I guess that this would let many not require to build vim from source. I would contribute a package myself, but being very new to Arch, I lack the how-to's of (high-quality) Arch packaging.