I have the Mariposa Plus and I carry everything I might need while on the trail (not camp) in the outside pockets.
In the long side pocket (left hand side wearing the pack) I carry my Rain Jacket, Pants, Pack Cover, Extra Water Bottle, etc. In the bottom right side pocket, I carry my Water Bottle, and lunch/snacks for the day. In the upper right (sundries) pocket, I carry my Aqua Mira, Purell, Headlamp (If I am hiking past dark, I don't want to have to dig through my pack to find it), map/compass, and other miscellaneous items I might need during the day.
In the front pocket I usually put my SpinnShelter and stakes. That way I don't have to open my pack and expose my other gear to the weather if it is raining. It also lets me store a wet tarp away from my other gear. In the cold, I also occasionally keep another layer in the front pocket so I can quickly put it on when I take a break. I will never own another pack without large external pockets, they are great for all kinds of things, and I am constantly amazed by the amount of gear that I can cram in them when needed.