In Oblivion the lock system was miserable, although the actual minigame wasn't bad the hard locks weren't all that hard in the long run. The skeleton key also aided in ruining the whole system. The first time I played through it took me awhile to actually find the skeleton key, by the time I got it I was already a lockpick master. However the second time I played Oblivion it was far too tempting to go over to the crappy god statue and get the key. (ruining the lockpicking mechanic, autopick, auto pick, auto pick, auto pick.) Would you like to have Skyrim share this same mechanic? I think that there should be really hard chest that poison you and even kill you if you fail. By doing this they could make some really awesome loot, hiding the chest and putting a really hard, deathly lock they could hide Umbra's sword.
I think it should be option number five.