One aspect of Heroica I found disappointing, despite all the fun of fighting monsters and grabbing gold, was the fact that your skill has little to no effect on the outcome of the game. While your decisions do have some influence on the course of the game, they're mostly limited to choosing what branch to take, and when to use a potion if you have one. I made the following changes that I thought made the game a little more fun when playing with friends, especially when multiple sets were put together (I only have two right now but it could work for more or less). All the dice rolling felt a little more fair when you could make small decisions to affect the outcome-
Each class gets Skills that a player can use on their turn. Each skill costs at least 1 Strength (hereby called SP) worth of slain monsters. You can only spend one monster per turn, so monsters with a Strength of 2 will give you more bang for your buck per turn.
Barbarian: Move 1 space for each SP spent.
Druid: Heal 1 HP for each SP spent.
Knight: Push an adjacent player back 1 space for each SP spent.
Ranger: Damage an adjacent player for 1 HP per SP spent.
Thief: Take 1 gold piece for each SP spent.
Wizard: Use telekinesis to grab something(e.g., gold, potion, key) 3 squares away per SP spent.
For longer games, you could do a very simple leveling system, where spending a certain number of SP unlocks a second, more exotic Skill for your character to use (For instance, letting the Thief sneak sneak past monsters). The skills I listed were just the one's we've used, but I've thought of a whole bunch of other skills, and it'd be fun to try to think of new one's every time you play and see how they effect gameplay.