That said, if resale is a consideration that you want to prioritize, my vote is for the finished basement IF it pushes your gross living area over a major threshold number. Allow me to explain. These days, buyers conduct their home searches by setting up automatic email alerts using websites like http://www.newenglandmoves.com or http://www.realtor.com. They enter basic criteria and receive property alerts via email on homes that match this criteria. For homebuyers who have a living area requirement, you won't be matched to them unless your house is of a certain size. So a buyer may specify that they want 1,000 sq/ft...or 1,500 sq/ft...or 2,000 sq. ft. All of these are threshold numbers. With each threshold you cross, your buyer pool grows...as does the number of prospective buyers receiving your listing through these email alerts.
In short, if finishing the basement pushes you beyond one of these threshold numbers you will have a better chance for success on the resale end because you will be matched to more prospective buyers. BUT, be aware that you will need to disclose in the listing that part of the living area includes a finished lower level.
If finishing the basement doesn't push you across one of these threshold numbers, then I think it's "six of one, half dozen of the other." Go with whichever plan suits your needs.
Why set your personal needs aside?
Our recommendation is to feature you and your family's needs before considering resale value. With a market in flux, calculating resale based on future buyer interest and needs is purely "guess work".......
Future buyer interest will pretty much depend on who walks through the door.
Make it work for you,