The z68 boards have use of onboard graphics as well as overclocking, and have ssd caching. Neither of which are a benefit, unless you want to use lucid virtu and only use your discrete graphics when you need it. Most people have no need for z68. There's pretty much no difference besides the allowance of onboard graphics in tandem with discrete graphics.
Edit: Sandy Bridge overclocking is all in the chip.
Edit 2: If I were you, I'd go with Asus. If your not planning to sli or crossfire, go with the vanilla board. If you are, go with either the deluxe or the pro. Take your pick of p67 or z68. It doesn't really make much of a difference because most people don't use the igp, and don't want to.
Edited by gregory121295 - 8/17/11 at 7:44pm