open top, or canopy ??? what do you want to keep?? LPS,SPS,Softies ???
If you have no limit on cash, the new LED Solaris are a great light, but for the basic reefer , halides will keep anything you may want for a reasonable price.
watts per gallon are pretty much a thing of the past, it's pretty hard to over light a tank, and if you do, you will need a chiller to cool the tank water as for high output systems generate a lot of heat. I have well over 2600 watts over my 8 foot 180.....
congrats on the 100th post.