Thanks for all the suggestions. To answer some of your questions:
- I don't want to add a rack to my bike because I also use it for training and racing (triathlon). Until I'm rich enough to have a separate commuter bike this one needs to stay my training bike first and foremost, so I'd prefer to not add any hardware.
- I don't want to ride to work in my workout clothes. I run over lunch, usually 7-9 miles, which gets the clothes pretty sweaty and nasty. I'd hate to have to put them back on to ride home.
- I've been keeping my running shoes at work during the week which is ok, but on Mondays and Fridays I still have the 2 pairs of shoes issue.
- I need to bring my laptop back and forth every day because I'm a computer guy and I do freelance work on the machine in the evenings.
- My external HDD can't be replaced with SD cards because I'm talking about 200 GB worth of data that I "need" available at a moment's notice.
I actually have been using a Targus laptop backpack with ok results. It has a bungee strap on the outside which is how I attach my shoes. That frees up the pockets for the rest of my crap. As for laying down the cash for a decent pack, I'm fine with that. I just didn't know if anyone had any specific model recommendations. I'm in Colorado, and do a ton of hiking in the summer as well, so this pack could well be used for other excursions when I'm not commuting. I'm mostly just trying to find that one elusive specific model of pack that will allow me to strap on two pairs of shoes via bungee or something, plus give me more room on the inside than I currently have.
Thanks again,
Matt