I know it costs a couple of dollars more, but when we travel I like the kind of milk that has the longer shelf life, like Parmalat. It's in nice quart sizes, but that way, you can keep maybe a couple chilled, and add more into the fridge as you need. We've also bought those little milk "juice boxes" in Orlando at Publix, and they were really inexpensive at the time. They come in plain and chocolate.
We mostly do soy milk, but for regular milk, the Parmalat kind stays nice and fresh when we're in a hotel room.