I've got a very nice set of matched roller luggage but have realized that I rarely use it. More and more I find a backpack to be far more convenient, especially for the low key--jeans, t-shirt, sweater--urban travel I usually do. I've been using my old school book backpack and need to get something better. Any suggestions for a good quality but not over-the-top pack for, say, a week of warm weather urban travel? I can get by very well on one or two changes of casual clothes, undies, small bag of toiletries, etc. I don't need things like a million pockets for water bottles, etc. Thanks!