OK, that's a long way, couple of days, and lots of bumps-braking-cornering, etc. Error to the safety side on your packing. The heavy boxes are a good idea. Invest in a couple of rolls of bubble wrap at Office Max-Depot-Staples. Wrap tops of bottles with Glad's Press 'n Seal. Better than Saran Wrap, because it's stickier and stays in place. Pack other stuff tightly next to the boxes to keep them from tipping over, but putting some Styrofoam between your booze boxes and the other stuff would be a good idea.

Good luck and have a good trip.