My wife and I frequently bring 12-18 bottles of wine from europe to IAD.
Declare it. Tax is $3.85 a dozen. I have never been charged. I frequently bring in commercial goods at the same time, and pay duty on the goods, but the wine has never been charged. I have had the duty on the wine calculated frequently, and it never comes out the same, or very much. A person tries to convert alchol percent to liters to gallons, etc.
For easy packing: Take an extra old hardsided piece of luggage. take sets of burgandy/champagne paper mache inserts, for both inside and outside each row of wine. Pack towels around the top and bottom, maybe a bit of bubble wrap on the outside. Get a good strap, and throw a tape wrap around the luggage. Make certain it has a good handle. 18 bottles weigh a lot.
I do not know anything about state regulations.