3 250W MH would be good and you would be able to keep most anything under them with good reflectors (lumenarcs and spider reflectors work well) as for spectrum. yes 6500k are good for growth but as you said they look ugly. i'd say 10000k is true white and other use VHO still for supplement. Corals need all spectrums possible to get good coloration. I use 14000k for the more blue look and i love the shimmer effect but to each his own.
6500k is for plants. You need at least 10000k for corals, but 14k and sometimes 20k if you like blue for MH. Also, three 150Ws would work, or maybe 1 250 and 2 150s. 3 250's is a lot of light, heat, and electricity output, and that could be overkill for corals. I wouldnt go higher than 2 250's and 1 150, but if it was me, I would go 1 250 and 2 150's.
you can use 6500k and everything i've heard corals grow like crazy, but they have no real color. most pet stors will grow corals under 6500k lighting and then move them to an actinic bulb for color then sell them. Corals need diff spectrums to get proper growth, but 10000k true white are the most preferred and apeasing to many.
I am ready to get the lights, but now I realize that I have a bar in the middle of my tank so I can't get 3 lights - would have to go with 2 (otherwise I would have a big black spot in the middle of the tank. What about 2 x 250 watts, or would I have to do 2 x 375 watts?
In regards to the light spectrum, I was reading an article (i'll try to find it) where the guy said 20,000 lumens really stopped his corals from growing. He recommended 6,500 or 10,000. 14,000 if you prefer bluer light, but personally I like whiter light instead.
What can I use for moonlights - are these bad for corals (i.e. don't corals need to rest without light sometime)?