The wall next to the stairs the way you have it now is strange, it needs a door there. You could also do a pocket door which means a little rework on the framing around the stairs but simple stuff.
While obviously you don't have plans on selling anytime soon the basement development is likely going to be in the $40-50K range so if you want this money to add to your house value you have to consider other people would consider value as well. A 14 year reno would be along the lines of changing flooring and bathroom fixtures and cabinets, knocking down walls, jack hammering concrete and moving plumbing would be a little extreme for a 14 year old house reno.
But anyway enough about basements, lets see some more tank progress
