Having to select "modes" for dungeons takes away a lot of immersion for me. I can see it now... *Huge UI pops up stating the name of the dungeon, a picture, and a checkbox for easy/hard mode* ... <--- F**K that! I want it to feel like I walked into a cave if the dungeon is in a cave. If it's in a forest, then I want to feel like I wandered too far out into the forest, and deep within I have become trapped in a settlement of monsters, a dungeon, and now have to EPIC-ly fight my way out. And also, having rare mobs or NM's would also be a good add to dungeons. like say a 1% chance of having X_Monster spawn, said monster would drop cool loot, and when it dies you get a buff. Etc etc..
Just make this game immersive, SE. That's what we all want. The true MMO fanatics. (I guess anyway, but I know I do!) I don't want a screen full of bars and windows, or menus and pictures. I want the game world in my face, I wanna explore, I want challenges, I want dialogue and voice overs all the time, I want epic quests that take me around the world to places I never knew existed.

Cheers yo,
your boy caM