With the current economic status, health care costs, and numerous personal reasons, it can often make sense to combine two households. With this trend has entered the demand for first floor bedrooms and in-law suites. Builders are building homes to meet these needs and homeowners are converting areas in their homes to accommodate their parents or are considering moving into homes with the features already in place.
Another "bonus" I see with having an in-law suite is the rental income potential. An extract living area with a separate entrance could be a great space for a tenant (or college child!) if you choose not to have a parent living with you.
Below is a home I have for sale in Aududon, PA. The garage was converted into an in-law suite with a full bath and kitchenette a few years ago. It's a convenient space for a parent or tenant with a separate entrance and set away from the main living spaces of the home. Click the photo for more details.