What is your favorite way to carry your "stuff?"
I've tried a lot of different ways, but probably not all of them. I've done the backpack, panniers, trunk rack, carradice pendle with a bagman support, and now my favorite - a carradice SQR slim that attaches to the seatpost. (Not really my favorite, because in the summer I can carry everything I need in my jersey pockets.)
I like the SQR slim because I can take it off my bike so quickly and easily. It's great for those days when I ride my road bike to work and I go on a club ride after work. I can leave the slim bag at the office and pick it up after the club ride. I have purchased a second SQR seatpost clamp for my touring bike (my regular year-round commuter) so that I can move the bag easily from bike to bike. I like the slim bag on the touring bike because it sits up high enough and out of the way so that I can use panniers on my rack in addition to the slim bag.
I think I've finally got my commuting "luggage" dialed in!