In need of more living space and you do not have the room to build out, well then remodel what you already have like your attic space, cellar, garage, sun room, or you can close in your carport.
Is your preteen or teenager wanting their own space away from their younger siblings. To keep the peace in your home you may want to consider remodeling one of the spaces mentioned above.
Needing a place for yourself? Just to indulge yourself, pamper, reflect on your life. There is nothing like your own private bath that you alone use. With proper planning this can be done in any of your spaces that are really not being used for anything else.