When you say "house lamps," what exactly are you talking about? If you're talking about table top lamps, leave the shades on them. It sounds like your light source is too small, causing the hard shadows. Keep in mind that the smaller the (direct) light source is, the harder your shadows will be.
As for the construction hot lights, you might want to take a look at Scott Smith's diffusion panel at
Lighting Magic . You could order his kit, or see what he's doing and make your own.