A walkout basement offers many advantages: it maximizes a sloping lot, adds square footage without increasing the footprint of the home, and creates another level of outdoor living. Families with an older child (say, a newly minted college graduate looking for work), a live-in relative, or frequent guests will appreciate the privacy that a lower-level suite gives. For maximum accessibility, consider a layout with an elevator. Walkout basements also show off a view lot.