Oooh, ok, so you are BRAND new to saltwater then! OK well, I highly suggest checking out all the stickies that are posted in all the sub-forums of the salt area, but for now I can give you a cliff-notes run-down of some very basic elements to saltwater...
Live Rock - this is the building block to most saltwater tanks, and all reef tanks. Live rock is comprised of rock and coral skeletons that are filled with living microscopic organisms, invertebrates, different types of algae - some desired, such as corraline algae, and if your lucky, sometimes there can also be tiny coral frags in the crevices as well, which - with proper care, can flourish before your very eyes. Live rock is used as shelter for nearly all fish, inverts, crustaceans, and several corals, as they anchor themselves to the rock surfaces and establish colonies. There are several types of live rock to choose from, and we can get into that later.
Live Sand - Well, just like live rock, live sand is "live" because it is filled with micro-organisms, plant and algal spores, tiny inverts, and loads of beneficial bacteria which aids in stabilization of your marine ecoystem (brush up on the nitrogen cycle and it will become clear).
Live sand offers far more benefits than it does drawbacks, and in addition to what it offers for cycling a tank, it also serves to offer a buffet of nutrition for several benthic animals, as well as shelter for burrowing animals. It comes packaged sealed wet in sea-water.
FOWLR - This is an acronym for "Fish Only With Live Rock". These tanks are self explanatory. Instead of including corals, plants, etc., these tanks are comprised of fish and live rock. Substrates very in these tanks from crushed coral, live sand, bare/dead sand (dry sand), gravel, etc., etc., and in some cases not having a substrate at all, but rather having a bare bottom - just the glass of the tank.
Reef - A reef is an entire ecosystem including fish, inverts, lived rock, live sand - and of course, corals. These are the most customizable tanks, as the combinations are endless. But they also require a good deal more chemistry to keep the system stable, and provide all the necessary supplements (Iron, Calcium, Iodine, Strontium and Molybdenum, etc) that corals, inverts, and fish alike require. Reef tanks also require more intense lighting, and that can get expensive initially.
What "looks best" is up to you, but if you are that limited for now, I would suggest a FOWLR tank, or even a FO - Fish Only, tank, of which you could purchase artificial rocks, plants, corals, etc. which will make it easier for you while you are still learning, more cost effective, and still offer a colorful and versitile display.
