Honeymoon trip deciding between Deep South US or New England?

I am considering honeymoon trip with my future husband in early to mid September- we want it definitely to be USA, we already visited Chicago, LA and Vegas. This time- I was thinking maybe NYC, cause it's a reasonable price from where we are flying, maybe see NYC for 3,4 days and then fly to Nashville from which we could take a roadtrip to New Orleans. I saw that plane tickets form NYC to Nashvile go for about $100, which is cool. I really like rock and blues, so the whole trip sounds like a nice vibe for it, plus the food.

Another thing I was thinking is New England, maybe Boston, New Haven, Salem, whatever is good to fit in within the roadtrip itinerary. We would have about 18 days of trip in total. I like both types of trips, I was just wondering if there is anything we could add onto whichever of these trips, any cool city to visit aside from mentioned.