When it comes to bags, bigger isn’t always better. And Tom Bihn’s new Co-Pilot bag is perfectly sized for those quick day trips when you need to keep things close at hand but don’t want to lug around a larger case.

The Co-Pilot is smaller than a typical laptop bag. But on a recent day trip, it was the perfect size for carrying my sunglasses case, a bottle of water, pill bottle, a GPS, extra shirt, papers and more. It’s still large enough, though, to carry a netbook or even my 12″ laptop.

The Co-Pilot features one main, zippered compartment with two open pouches, making it easy to organize gear and other necessities and keep them close at hand.

There are three zippered compartments on the front. One has a soft Ultrasuede-lined pocket that’s made for an iPhone or other cell phone, with room for a small toiletry kit, as well. Another front compartment will hold a small water bottle or a compact folding umbrella. And a third includes pen pockets and an o-ring to attach a key strap.

An open-top pocket on the back of the bag will carry a newspaper, magazine or book and still easily slip under an airline seat. The outside of the bag is made of abrasion-resistant ballistic nylon. All Tom Bihn bags are manufactured in Seattle.

The Co-Pilot sells for $110 in a choice of five colors and includes a standard shoulder strap. The optional Absolute Shoulder Strap ($30) has some extra “give” for carrying heavier items, with a patented control-stretch system.

Other Tom Bihn bags I’ve reviewed, including the checkpoint-friendly Checkpoint Flyer and the Tri-Star Travel Bag, have impressed me with their design and quality. The Co-Pilot carries on that tradition.