Panniers vs. Backpack for commute

[amandar]

One vote for saddlebags, although with a laptop you will have to get the largest carradice.
I use an Acorn med/large saddlebag, and it is awesome. All I need to carry is a shirt, pants, wallet, keys and tools though. I can also lash a jacket to the outside. If you're a minimalist it's plenty big.
The only problem is where to put my shoes. I currently wear my shoes (chromes) when commuting. One of these days I'm switching back to clipless, and then I'll have to leave a pair of shoes at work.
My bike comes into my workplace with me, so theft is not an issue. If it was I'd remove the seatpost and bring the whole thing in.
Carradice bags are huge, I can fit shoes, pants, jacket, food, tools, etc. with room to spare into a long flap.