2/ An extra Bedroom
If you have children, most kids will reach a point where they can't share a room with their sibling or want their own space separate from everyone else. When this happens, your attic would make some of the best areas for constructing an extra bedroom.
On Pinterest and other sites, you may find plenty of remodeling ideas to help you find your preferences. You can also build it base to follow your home's current style. If your attic is large enough, you can make a bedroom for each of your children and design it with their favorite decorations.