Ok, Based on a suggestion from Creefer in the "Let's talk sticks" thread lets talk about acro placement. There are many factors when it comes to placing new acros in your tank. Lighting, flow, and relation to other corals are some of the main concerns. There is a ton of anecdotal information out there but really very few hard and fast rules. First and foremost when acclimating a new acro I take into consideration lighting. It is huge important to acclimate your new coral to your specific lighting very slowly. The easiest way to do this is to start the coral on the bottom of your tank. Once the coral seems comfortable you can slowly move it up into higher light. Exposing new corals of any kind to lighting that is much stronger than what they are accustomed to is a recipe for disaster. Most coral will tolerate extremely strong lighting if they are acclimated slowly and allowed to adjust.
The next factor I take into account is flow. A rule of thumb that many use based on anecdotal evidence is that thicker branched acros prefer more flow. However this may be incorrect. Heavier flow tends to cause acros to build heavier branches. It stands to reason that one would assume that the thick branched acro preferred to grow in the heavy flow when actually the thick branches are a result of the heavy flow. With most acros enough flow to make the polyps "Dance" is usually enough. To much direct flow will reduce polyp extension and in extreme cases blow the skin right off them. Too little flow usually results in poor growth and in extreme cases tissue recession.
3rd on the list is placement in relation to other corals. I take into consideration several factors. Will neighboring corals grow faster than the coral being placed near them? If so will they grow over and on the coral? Will they grow large and block light or flow from the new coral? Do they tend to base widely or grow upwards? Are they a dominant coral with a powerful "Sting"? Do they have sweepers and can they reach the new coral? Lastly, do the colors contrast which will make both corals stand out making the display more appealing to the eye.
I am sure others have some input so I will stop there for now.