I commute year 'round and have to lug a laptop for which I use the Jaand laptop bag. It's worked very well. The only complaint so far is the little rubber thingies that protect the rack from the hooks -- they slide off. Opposite the computer bag is my grocery pannier with my work clothes and miscellaney. Now that it's warming up, i have room to pick up small numbers of grocery items. But, I usually leave groceries for when I get home and can have the boys go with me on their bikes.

The bags are heavy, but it makes me much faster on the weekends after lugging that load around.