Few things give a house more character (and practical storage) than built-ins. Whether it’s floor-to-ceiling cabinetry, window seats, bookcases, or even desks and media surrounds, built-ins are stately, practical, and, depending on build quality, can last decades if not centuries (yup, that long). But what do they cost, who do you hire to install them, and is there a return on investment for your home value? We talked to four experts, from real estate pros to interior designers, to get the scoop.