scaffolding & redstone

The scaffolding could be used to place redstone components both underneath it and on top of it, allowing circuits to be separated by levels. For example, a 9-block-tall contraption could be reduced to 5 blocks tall because this would remove the need for an extra layer of blocks to support and separate the next level.

Edit: Now that I think about it, a NOT gate would be great if the idea above was added, because the traditional block + redstone torch design wouldn't work. The block would be powered, so you wouldn't be able to place redstone on top of it.

Another thing that would be great is a bridge block (maybe similar in appearance to a repeater/comparator) that allows two separate signals to cross without connecting, removing the need to build actual bridges out of blocks.

I think these would make redstone contraptions smaller and cheaper in Survival because players wouldn't need as many support blocks or large bridges just to bring a signal from one place to another.