What type of plants are they? Some of the oddball ones that I have to bring in when the weather cools off seem to go through a dormant phase and then REALLY take off again when I put them back out in the spring. I don't know if that's something natural or if I'm forcing it by the simple fact that I'm bringing it into my sunroom (it's cold out there but doesn't freeze and doesn't get much light after 11am).

In addition to lights for plants that will be in a warm spot (so they don't go dormant) you might want to consider air moisture and circulation. Most homes are dry in the winter. If you run a fan set on low 4-6 hours daily and place a few shallow bowls of water around, the likelihood of developing aphid or mealy bug infestations will be reduced.