One major planning area for basements is how likely it is to get furniture down basement stairs. Especially in older homes, the stairs leading to the basement are narrow, and you need to make sure you will be able to fit the needed furniture down before you commit to a remodel. Pick out some sample pieces and measure them against the stairway before you begin the process of finishing the basement.
Basements do not count in the square footage of a house for assessment purposes. An underground room is considered "not livable" in most areas, though certainly a well-finished basement is livable space. If your plan is to increase the asking price for a house you are selling by finishing the basement, weigh that possibility carefully as the assessed value of a finished basement is much lower than the value of above-ground square footage.
Though the additional assessed value isn't high on basement property, the actual value to buyers is higher. A buyer who wants an office will count the basement office because the space is usable. For the time being, basement space gives your family room to grow without needing to build onto the house. Finishing a basement is far less costly than building an addition, and much of the work is doable by even a moderately-skilled do-it-yourselfer.
Flooding can be a real problem in basements because of cracks along the foundation or other problems. When planning to finish a basement, have a foundation specialist look at the home before making any investment in the process. Skimping on water-proofing can lead to dangerous and costly repairs down the road.
Basements can have any number of uses depending on the time and money that goes into planning for their finishing. A finished basement works really well as an area that can be cordoned off easily. Home offices and game rooms are two common uses for basement space because the people who use that space can head down and enjoy it, but the rest of the family isn't obligated to tag along.