You guys that have gone on tours before.

Best thing for the long drives:

A European tour we did last summer with A Life Once Lost had some long drives. just us and them sharing a small van.
One of those dudes had spoken word shit that was awesome for the long rides. John Joseph (that right?) from the Cro-Mags was awesome! Henry Rollins one was good.....+ R Kelly in the closet

Put that on the stereo and everyone just shuts up apart from the odd bit of group laughter. Real good
 
+1 on the Socks.. and Boxers!
Battery's, extra cables and strings.
take 1 or 2 shirts for on stage, leave it like that.. or else you'll be out of shirts reeeaal fast.
And a beany ton put over your eyes or something, realy helps you sleep in a bus.
Next to that.. superglue... for putting stuff on the sealing in hotels :)
 
what everyone said....stuff like febreeze, toothbrush etc, socks and underwear obviously, medication for diarrhea (sp?), headaches...

go easy on the alcohol, playing hungover ain't no fun.
try to eat as healthy as possible, getting sick on tour is a major PITA.
I envy you