Finished Basement: house, drain trap & vent

Couple of thoughts: - Paint the pipes the same color as the wall and see if they disappear to your satisfaction - Use some sort of a series of panels that move back and forth along a track (similar to closet doors in newer homes). I admit the overhead looks pretty cluttered for that one. - Since the bottom of the "U" appears to be not more than 32" from the sill, using eyebolts, hooks, etc., as appropriate, hang a hollow core door or 2, on edge, from the overhead, outboard of the pipes. Though it would create a slant, you could easuly work out a system to cinch the bottom back toward the wall, - Personally, I'd paint them

I can't see the photos, so I'm guessing:

Hopefully you'll go many years between needing access, if ever. Why not frame and drywall over it? When and if the day comes that you need to get in there, drywall is cheap and easy. Well, easy compared to sliding panels, doors, false walls, or whatever else that you might only use once in ten years.