Re: Good spare parts to carry.
Extra sticks (derp), cymbals felts, sleeves, wing nuts, t-rods, washers, drop clutch, two extra BD beaters, about 4-5 keys, Excedrin Maximum Strength, a couple of towels, gorilla glue, multi-tool (Gerber), 1/4" socket set (metric and SAE), and moon gel. I think I have a new P85 in the tool box too with a bunch of snare cord and straps.
I also keep some spare guitar parts...strings, tuner heads, etc. Never know and I'm already carrying a tool box of drum parts, might as well keep other stuff in there too.