For long rides (100-200 miles solo and unsupported) I take an Arkel TailRider with a builtin rain cover. It contains the inner dry bag from the Arkel saddle bag I use on shorter rides, one liter Platypus, Clif bars bringing my total to one every two hours, sun screen, what I don't wear during warm daylight hours (wind jacket, thermal jersey, thermal tights, reflective ankle bands, reflective vest), spare Garmin Edge 500, spare cue sheet, Krebs bicycle touring map, spare tire, electrical tape, helmet light, Ixon IQ Premium as a spare head lamp, 4 AA batteries as spares for that, spare phone battery, handlebar phone holder.

For all rides:
My small dry bag has two tubes, a patch kit with sealed vulcanizing fluid tube, three tire boots, two tire levers, three master links, the left over links from a new chain, Park MT-1 dog bone, T-25 torx key, chain tool, spoke wrench, TiGr lock cylinder, and a pair of nitrile gloves.

Outside those I have dynamo lights with no batteries to exhaust, a full-sized frame pump (90psi in 90 strokes) beneath my top tube, and my TiGr titanium lock bow.