I feel obliged to put in my bit.
I, for example, abhor the thought of pvp unless we are totally on equal ground, such as fist to fist, no weapons no armor. Other than that, I would kind of like the Idea of Pvp, as many of you mentioned, it would create more of a sense of "survival" part of the Survival.
I have an Idea. What if the Hardcore Server was, as it is, entirely pvp; but also add things that Survival has such as mcMMO and such.
I would, personally, like the idea of having certain "Teams". Once you join a team, members of your "Team" can't hurt you, and yet you can grief the other team and such. you could build towns and even cities that are secured. Now I could get into that