What exactly is your goal?
Do you like the wall of rock look?
Do you enjoy having alot of fish?
Is your focus more on corals?
1. For the wall of rock, you just need to have it stacked up so your corals can be placed in different areas. Remember to leave room for fish in the front. This is pretty common for many sps'ers.
2. For the fish enthusiast, you might want to keep your rock no higher then half way or maybe a little higher in key areas. This gives your fish the ability to have some nice unobstructed swimming area. That's how I did mine but unfortunately, a few corals grew insanely large and now block a portion.
3. Focus on corals either is wall o rock or have your in different levels. Obviously, the higher your rock, more corals you can have.
Plan for powerheads now. No point in buying cheap to just upgrade later. It adds up. Personally, I like having small footprint. I ended up with 2 Vortechs. Suckers kick out the flow and barely notice them on the tank.
Couple tidbits of advice.
1. If you plan on doing SPS, do NOT put mushrooms,xenia, anthelia, or green star polyps in your tank. If you can keep any of these isolated, you might be fine except for the shrooms. You get one of these as a floater into the middle of your rock formation, you will go absolutely nuts.
2. Zoos. Keep them isolated where they don't get invasive on your rock. They can crowd SPS but generally don't kill.
3. Most of all, buy what you like. No point in jumping on the hype unless it is a nice piece. I still havent bought a purple monster because I just don't see the whole big deal in it.
4. Patience. I would let your tank get cycled and then wait about 3 months. Grab a green slimer or a cap from someone and see how it does. If you get growth and good color, then try another piece.
Just a few tips. If you got any questions, just post em up.