Buy in bulk. One 32-ounce bottle will use less packaging than two 16-ounce ones, even though the total size is the same. Plus, the larger bottle will probably cost less per ounce than the other two combined! For an example, let's look at pop. A 2-liter bottle of pop costs $1, or about 1.5¢ per ounce (there's 67 ounces). The packaging comes to about 163 square inches. Opposing this is the 12-pack of cans. The cost is about $3 for 144 ounces, or 2.1¢ per ounce. The total packaging here comes to 600 square inches! The 2-liter is much better! Less cost per ounce, and a lot less garbage in the landfill!

As always, Please feel free to comment with any questions or anything to add!