If you have a fave jeans, go with that because they are durable and functional while still chic and fashionable. A great pair never goes out of style. Also, they work for various climates. If you're in the balmy west coast of the States, or the brisk bulstery pre-winter east coast, jeans are versatile.
Finally, a great tote or saddle bag completes the look. The saddle bag is best because it keeps your hands free as you add more bags throughout the day and can be worn safely and comfortably at your side the front. A big tote also can be worn on the shoulder and are also good for freeing the hands.
Good luck and happy shopping!