The wiring is the key and your desired end result is going to be critical. Most builders have something they 'like' to work with, so ensuring that you get a custom A/V installer who can actually help you get the desired results you are after is critical.
It is also a good time to think about whether you want to do a distributed video system as well.
If the home is new construction I would avoid the pretty rack, and try to put a space in your home with good ventilation where all the gear can be hidden or accessed from behind. Rolling racks can be troublesome in the long run if not done properly, and you want to ensure that you have enough room to grow the system as your needs require.
Most of all - above all else - very important - this means you...
Wire your home!
Don't just kind of wire it, but ensure that you wire it fully and if at all possible put conduit in place between critical locations for future wiring possibilities.
Cat-6 wiring is cheap and putting in 3-6 runs to each display can be invaluable in the long run.
Decent speaker wire anywhere and everywhere is a good plan. Even if you aren't using it now, just having it there can really be beneficial in the long run.
I am amazed at how many builders claim knowledge and don't know what they are doing. Moreso, I'm amazed at how many A/V installers do the same. Properly designing a 8-16 zone system which allows you the future growth you may want and provides you the insight to get some ideas into your system which you hadn't previously considered is extremely important and can be difficult to find.
Here you are on an A/V board and see how many responses you've received already?
