You will likely not recoop the cost of the basement finishing, at least given current market conditions. If you have a walk-out basement with 8' ceilings, you will recoop more cost than you would if you have a 100% below ground basement with 6.5" ceilings. If you haven't finished it yet, I would suggest adding a bedroom (or a room that can be used as a bedroom or left open a la French doors) and including a closet and window in that room in order to maximize value - Make sure you do include that full bath.
If you are renovating just to renovate and add value to your home, don't bother, especially in this market. If you want to renovate to get extra usable space and for your and your family's enjoyment, then I say have at it and do what you want to do for the money you want to spend, just don't plan on getting much of it back.