Replace your current plain acrylic diffuser with textured glass, stained glass, etched glass or alabaster tile. This alternative works especially well if the fluorescent light is a ceiling light. Opaque white textured glass or alabaster creates the softest glow with the brightest light; etched glass has pockets of very bright light and "barely-there" light, depending on how much etching was used; colored or stained glass diffuses your light the most, and casts interesting colored shadows that give a semblance of drama and mystery to an otherwise bland space.
Modify a long rectangular wooden planter hedge box--a good alternative if the fluorescent light is mounted on a wall. Remove one long panel for light to be upwardly directed, creating a diffused glow; remove one long panel and the bottom panel for light diffusion upward and downward. Attach the box over the light with strong glue or L-shaped brackets; it should look like a long sconce.
Enhance your acrylic panel diffuser; trace a stencil over contact paper, cut out the pattern with a craft knife and attach to the inner panel. Paint the whole panel with watercolor; when dry, peel off the contact paper. Watercolor is translucent and allows some light through, creating a diffused glow.
Use glass blocks with any interesting pattern and color of your choice over a floor light source (clubs, executive suite hallways, upscale homes). Glass tiles are not a safe option where feet can kick in a crack.