It’s hard to believe that the modern minimalist dining and living rooms pictured here exist in a 12,263-square-foot French Tudor-style home in Memorial Villages, an affluent section of Houston. “This was an $8 million spec house that we came in and fixed,” said Nina Magon, principal and creative director of Contour Interior Design in Houston. The owners, the co-head of an energy investment company and a rheumatologist with two young children, love to entertain and asked Ms. Magon to incorporate “stand-out pieces that look like art” from “top designer brands” in the design of the two rooms. Which she did, at a total cost of about $534,600. “It’s a little different for this area. You generally don’t see spaces designed like this,” said Ms. Magon of the results. “The rest of Houston will have to catch up to this design.” Here are some of the rooms’ costs.