Nashville Best (2 nghts): Margot, Mambu, Zola?
I'd rank them Zola (best), Margot, Mambu for food, and Mambu (best), Zola, Margot (last by a long shot) for ambience. Some people swear that Margot is the most romantic place in the city, but I find it loud, with tables right on top of each other, unless you can get a table upstairs. Mambu is where I go for my own anniversaries, Zola would be my second choice, but you won't really be sorry if you go to any of them.
I would go Margot, Zola, Mambu. I have only been to Mambu once for lunch and was not impressed. I prefer Margot to Zola, but I think it's a matter of food preferences. Margot is more influenced by French bistro cooking, while Zola seems to lean more on Spanish cooking. I find Zola offers more bold flavors and combinations, while Margot is more restrained and refined. Margot is definitely "cozier" than Zola, but I've never felt cramped in there. Enjoy.