The future of work is rapidly evolving, particularly in knowledge-based professions such as programming, engineering, and scientific research. These fields traditionally rely on physical monitors in office settings. However, with the rise of hybrid work models fueled by technological advances and the COVID-19 pandemic, there is a growing need for flexible and portable display solutions. Workers can now operate from remote settings, their homes, or mobile scenarios while still requiring substantial screen space to complete their tasks. This dissertation investigates the design and evaluation of virtual displays rendered through head-worn displays (HWDs) as a promising alternative, aiming to optimize them for productive work. These displays offer flexibility, allowing users to achieve large monitor spaces in virtual or augmented reality environments, adaptable to any location. We aim to answer three research questions: (1) ``How does replacing or extending physical monitors with virtual displays using current technology impact the user experience of productivity tasks?'', (2) ``How can we take advantage of the spatial flexibility property of virtual displays to eliminate screen boundaries and increase the amount of space available to users?'', and (3) ``How can we leverage properties of virtual displays to design techniques that minimize overhead in window management tasks without reducing user freedom?'' Through careful interface design and empirical user studies, we seek to understand how to leverage the unique capabilities of HWDs to enhance productivity, preparing the groundwork for future virtual display systems as technology advances. / Doctor of Philosophy / The future of work is rapidly evolving, particularly in knowledge-based professions such as programming, engineering, and scientific research. These fields traditionally rely on physical monitors in office settings. However, with the rise of hybrid work models fueled by technological advances and the COVID-19 pandemic, there is a growing need for flexible and portable display solutions. Workers can now operate from remote settings, their homes, or mobile scenarios while still requiring substantial screen space to complete their tasks. This dissertation investigates the design and evaluation of virtual displays rendered through virtual or augmented reality headsets as a promising alternative, aiming to optimize them for productive work. These displays offer flexibility, allowing users to achieve large monitor spaces while being adaptable to any location. Our research aims to understand how replacing or extending physical monitors with virtual displays impacts productivity, how to maximize the available space and organization, and how to design techniques that make it easier to organize and access windows. Through careful design of these displays and testing with users, we seek to understand how we can take advantage of the capabilities provided by AR/VR headsets to enhance productivity and pave the way for future displays.