Lighting is complicated, and none of the advice given is usually decent. It's not because they don't want to help, it's just because there are way to many variables in the equation. Distance, bulb shape, spectrum, water clarity, positioning, ambient lighting, and many more all play a part.
For instance, I have a 65G tank that had a 19W normal fluorescent light on it, probably 6700K. At the bottom of this tank (2' or so from the light) I had some mushrooms and palys grow from the rocks as hitchhikers. Most guides would suggest about 20 "times" that lighting (in terms of lumens, which are a bad guide, but better than W/g).
From what you've written, your tank doesn't have anything that needs lights. So 1 blue, 1 white (look for 10000k for the color) would probably look good, but looks are all that matter for FOWL. Crabs, stars and urchins are not photosynthetic so don't need any lighting, other than to see and be seen. SPS, LPS, Zoanthids, mushrooms, etc need lighting and finding out the right amount is hard and subjective. There's enough to keep them alive, enough for them to look decent, enough for them to thrive and enough for them to look amazing.
Coraline algae tends to not like MH lighting, if you get MH lights expect it to all turn white then start to grow back on the bottom 2/3rds. To get it to grow keep the alkalinity of the water up (mine took off at about 9-10) and the calcium at 380-420, give it a few months and you'll be complaining about the coraline. Once the growth starts, check your alk and calcium daily since it'll deplete quickly.
Now, all I've written is based on my experience (limited), reading (extensive) and wont apply to you (see the first paragraph). Read a lot, then try something and pay close attention to your tank.