My setup for 1-2 week long road tripping:
Side cases had my waterproof gear, tool kits and clothing. Top box had spare gloves, maps, camera, water, an extra sweater and anything else I wanted quick access too, with space for any groceries I pick up on the way. Dry sack has sleeping bag, pad and pillow. Purple bag is a Marmot 2-man tent. Yes, there is enough space between the dry sack and the tank. I'm a small dude
I don't carry food, except for a few pre-wrapped snacks. I'll get enough for a meal once I arrive at my destination. It's not worth the hassle of having critters clawing at your bags to get at anything they can smell, and I've done enough canoe-camping to see the kind of damage they can do.
My tool kit includes a tire puncture kit, pressure gauge, chain lube and tension adjuster, and a handful of wrenches and allen keys for doing basic maintenance.
Generally what I do is pull out everything I think I'll need and lay it out on the floor, then start trimming until it'll fit on the bike. Remember to pack your weight as low as possible, and try to keep it evenly distributed if you're using side cases. Always leave a little extra space too, for food pickups and anything else that may happen on the way.