Some of the bread machine recipes that I use only call for water, but then it says to add a little powdered milk to the dry ingredients. I think it might make a little fuller body on the bread, and maybe healthier, if it is made with milk instead of just water.
I have tried variety in my recipes with other ingredients, as well. If it says butter, and I only have a dab left, I have used olive oil instead' and the bread came out just fine.
I like to add a bit of shredded carrot to the recipes, and sometimes herbs, like oregano and garlic, for a bread that is going to be eaten with soup or stew.
If the bread is coming out hard, and not rising, maybe the yeast is not working. Get the little jar of yeast, and not the little packets, and then keep it in the refrigerator, so it stays fresh. Be sure the water in the batter is warm, and that there is sugar for the yeast to feed on, and then see if it rises better.