I've never made my own Spaghetti/Marinara Sauce. I do however know someone that does and they make enough to home can quart portions for future uses. No thin/watery Marinara Sause in their house.
As for me an above average Marinara Sauce replaced Spaghetti Sauce years ago. I too like to add things like mushrooms, chopped onion, and Italian Meatballs when I make linguine or spaghetti.