I haven't read through the whole thread, but I have "spiffed" up many spaghetti sauces using jarred sauces. Prego is my favorite, even though I have used Hunts many times, along with off-brands. I like to add garlic powder, more italian herbs (especially basil and oregano), sugar, and sauteed vegies (onion, pepper, mushrooms, garlic).
I have never thought of adding wine, unless I was making a crock-pot or oven slow-cook recipes. Good idea!
I have even "spiffed" up jarred spaghetti sauce for pizza!