I don't think fish care either, though I feel better when gradually increasing light, be it through staggered lighting or starting the light cycle after the tank gets ambient daylight. I figure its not as stressful for fauna as going from complete darkness to bright light.
I like 5000K for dawn and 5000K+actinic or blue cold cathode for dusk. Overlapping bulbs during transition will increase photosynthesis, and you can limit growth rates while keeping color by controlling the overlapped period (the "noon effect"), so in the end it can be better to just use 6700K and 10000K because its a more pleasant combination than either with 5000K.
If its a custom hood, an incandescent on each side could be neat. Say the left is on for 30 minutes before mixing with the main, then turns off, then for sunset the right incandescent turns on and mixes, then stays on until switching to moonlight. Incandescent (or screw-in CF
) is attractive since it won't take up too much real estate in the hood that could be better used for flourescents during the noon or regular photoperiod.
Its a fun thing to mess with and can be cool for the viewer, but for me it lost its novelty after a while. Its also a pain to squeeze in a bunch of timers on one light strip. Definitely neat to watch and can add to the experience of a "natural habitat," especially considering your interest in biotopes, though.