Wireless in a business environment requires someone with excellent knowledge to secure the system, otherwise, it's wide open to hackers.
This is a wide open question with as many potential answers. Ultimately, an optical network would be at the current leading edge, but would be an overkill (in my view) for an average business.
As my title, it all comes down to what he wants to achieve!
Establish his goals and then determine the best course of action.