Icewind Dale: Heart of Fury
Make enemies much stronger yet reward more XP and more powerful items. This would obviously change the max level of the game. It never felt like a low level campaign to me so I would appreciate that.
Place additional difficult encounters on the map. I would like more difficult non-story encounters anyway. Running into a full powered Beholder in the underdark would be nice. I liked Gothics approach of using strong enemies as an alternative to "you cannot go here yet". Don't force players to deal with such encounters but let them stumble upon them sometimes. One of the companions or the narrator could point out that it would be foolish to go there. As it stands now the enemies are adjusted very well to the capabilities of the players group. Finding a way to avoid an encounter can be just as rewarding as fighting. I think it furthers immersion when your group cannot simply eradicate every single creature on the map.
