I'd like it if there were some sort of rankings for dungeons.
It would be too boring to simply mindlessly grind them for items or resources. So how about instead reward players a bit if they were the first guild or party to clear a certain difficult dungeon? A flying mount?

Naturally you'll lose it if someone else beat the dungeon quicker than your party.
This game is about competitiveness right? Risk/Reward and all that.