Well there are a couple of factors that you personally must consider when looking at TV's. I say this because you pointed out that it will be on quite a bit and power usage is a concern.
After reading your post, LCD is the choice I would go with. Here are my reasons.
Plasmas use more power than LCD TV's. Also with Plasma TV's you have to worry about ghosting or burn ins.
Screen burn-in - Wikipedia, the free encyclopedia
Plasma vs. LCD: Which is right for you? - TVs
Two interesting links above. Check them out. The second link should be a deciding factor.
Rick