I use an EMS Short Circuit backpack cuz I need to carry a laptop. Has shoulder and waist straps. The laptop zips into it's own compartment in the back (the padded part against your back) which is handy at airports. If I know I'm running errands and collecting lots of junk after work, I use my messenger bag (Manhattan Portage) and toss my laptop in it. And if I'm just riding long distances and need a hydration pack, I use a Camelbak Blowfish. The Blowfish also comes in handy skiing, snowboarding, sightseeing, hiking, etc. The messenger bag just holds lots of stuff and I can use it as a weekend bag.