Cristina Santamaria prides herself on keeping her clients in the loop — in Spanish as well as English. People never have to track her down for an update.

She takes the same approach with all of her clients: First-time buyers, investors, and sellers of multimillion-dollar penthouse condos receive equally careful attention. She points out that the person is the client — not the property — and that real estate is a people business. People need the s...