I've done backpack on me, mess bag on me, rack trunk, backpack in a grocery pannier on the rear rack, backpack strapped directly to the rear rack, saddlebag panniers, milk crate... haven't had the pleasure (or finances) to explore the Carradice type of saddle mounted bags, nor have I tried any front loaded options.

Of all the ways that I've experimented with, the set-up below was perhaps the most versatile for when I had a multimodal commute, though it did have an impact on the overall performance of the bike if it was too heavily loaded. I now have another beverage crate that is shorter (same length as the rack platform) but the sides are a bit taller (but not as high as a milk crate). I think my next experiment will be with the shorter crate and split the load between me and the bike- I'll carry my essentials and high value items on me and use a waterproof stuff sack for layers to put on the rack.