As a regular Sacramento traveller I carry wineskins (plastic, bottleshaped, bubblewrap inside) to carry my Napa-detour loot home. We always put it inthe centre of our bags, usually in among the contents of our "dirty laundry bag" to give it extra padding, and we try to avoid connections: doing SFO-YYZ rather than a SMF-DEN-DET-BUF hopscotch.

Any winery in Califorina will sell you wineskins.