Gauntlet of Shar, Moonrise towers and below. Lots of challenges, and it is exciting... for a while. But after so many retries in every battle,
it would also be nice to get on with the story, the romance, the unravelling of the sinister plot. So maybe add a difficulty level where, for instance, the nightsong actually can do something instead of getting swatted like a fly. Or where my strongest member (Lae'zel) doesn't get killed in one turn by the Myrkul prophet. You could leave her with 1 HP and have her continue happily with that for several turns, like you do with the bad guys.