There are some great ideas posted. My husband does not appreciate it when I try to improve on something that is fine with him the way it is. And if two recipes are too similar he will stick with the old familiar one almost always. Still, there's a lot of territory out there to be explored!
I have found that carrots, sweet potatoes, pumpkin, butternut squash and acorn squash substitute well for one another, especially in sweet recipes like pies and muffins. For something a little different, how about...
Sweet Potato Cornbread
2 tbsp oil
1 cup mashed sweet potatoes
3 large eggs
1 1/2 cups milk (your choice)
1/3 cup oil
3 cups self-rising cornmeal mix
Preheat oven to 375. Place 2 tbsp oil in skillet and heat in oven for about 10 minutes.
Meanwhile, combine potatoes, eggs and milk, mixing until smooth. Add oil and cornmeal, stirring until just blended.
Pour into hot skillet and bake until golden brown, about 40 minutes.
Do you see how you could do something similar with biscuits? Maybe just a 1/2 cup of pumpkin stirred in. Adjust the spices to be savory or sweet, too.
I love to use fresh green herbs. Herbs are nutritional powerhouses, as are spices. One of the best ways to improve health is to use herbs and spices as often as possible. Chives, parsley, cilantro and basil impart a fresh bright flavor, aroma and wonderful color to a dish.
Just before serving soup I like to shred a little zucchini into it and toss in the green herbs. It's pretty.
You can also put veggies in the blender and then add them to all sorts of things, in moderate amounts. I have a child who shudders at chunky tomato sauce, but loves the same sauce if it has been pureed. Tastes the same, but the texture is smooth.
Last hint: halve the recipe. If it bombs, there is less to choke down.