Picture a coffee shop on the ground floor with apartments above it, or a row of townhomes where each owner runs a studio or small office from the front room. Those are mixed-use and live-work properties, and you'll find them in historic downtown blocks as well as newer planned developments.

Real estate has long been one of the ways people build wealth they can see and touch. A well-chosen rental can produce income, gradually pay down its own debt, and come with tax advantages that many other investments don't offer. It also carries real responsibilities and risks, and it isn't …