I'm with you about not having important spaces look like afterthoughts. I finished our basement and have attempted to utilize all of the space.

Photos can be viewed from the link below and many have comments. Here are some of the items I used to hide necessary features yet make the space useful:
A wine rack which, when removed, permits service to an exhaust fan.
French Doors - one set for a storage room, another to disguise a laundry tub sink and permit access to storage below the stairs.
The right side of the fireplace opens via a piano hinge attached to the wall. The corner trim is attached to the door and runs floor to ceiling. A full width shelf inside permits storage of long items and framed art.
A flush door enclosing the electrical panel is deep enough to store folding tables.
A bookcase on casters rolls forward to service the furnace.

The photos include a floor plan which I believe is the critical element for a build-out. Hope some ideas work for you. Good luck.

Here is a link that might be useful: Basement Photos

Yes, they do sell doors separately, and you can have them made to the size and style you need. You probably have a local woodworker supplier that does this. Or try Rockler.com.

Trying the local route is probably better for getting all your questions answered.