Backpacks-for travel?

I am in the market for a backpack to use while traveling in Europe. I have looked at the Dakine-Jewel backpacks, and I love their prints. Are there similar backpacks, perhaps a different brand, or maker? I would love to have something that's around 19-21 inches, since I will be using it as my Carry-on, as well as while walking the cities.

THREE REQUIREMENTS:
1)Great Prints
2)Must be able to lock zippers. (To keep thieving hands out)
3)Needs to be of good size. approx 19-21 inches

Go to Jansport.com, they have everything you need. As for locks though, you can use a keyring (like on a key chain, but just the ring part). A really thick and durable keyring. Or, you can use a combination lock. Make sure that: 1) it fits through the holes in your zipper, and 2) you don't forget the combination!!!.

You could also check a stationary store. Sometimes they sell diaries with little locks on them. You could buy the diary and use the lock off it. I did that once. I kept the keys on a skinny little chain that I wore around my neck and kept hidden under my shirt.