At the end of the day if light is limited then you have to give it to the plants that need it most. So the question would be what are the other plants? Are they high light plants like cattleyas or lower light.

If the phals are spiking anyway then they probably do not need the extra light to flower but would probably give more/better blooms if given the extra light.

Bright light can actually shorten the life of blooms, although I suspect that the light from fluorescent tubes is likely insufficient to cause this effect.

Nonetheless, flowers don't need light - it's the leaves that need the light. If you've managed to get something to spike and bloom, then the light levels are just fine wherever they were growing. Unless you're using the light to change the direction of buds (and some people do this rather than staking), it's usually not advisable to change light levels when buds are forming.

Thanks for the responses - the other plants are cattleya hybrids and dendrobiums, and oncidiums, and who knows what. I have a little bit of everything!