Things I always carry to a show:
QEW or ONR, and some regular car wash (Poorboy's SS&S)
Poorboy's S&W
QD's: Quik Shine and Spray & Gloss
Plenty of MF's and WW's
Some trashier towels for wheels, etc.
Tire dressing and an Eagle One tire swipe (I usually don't need to re-dress, but just-in-case)
A lint roller to pick up anything on the floor mats/trunk mat
I put all of the above in small 2 and 4 ounce plastic bottles, some with fine mist sprayers for the QD's/S&W, and keep them in a Ziploc bag.
If I'm going out of town, think there might be a possibility that I'll want to wash and won't have access to a hose and buckets I also bring a couple of buckets and wash mitts.
If the hotel doesn't have a hose then I find a coin-op car wash where I can at least rinse the bugs off before I do a regular wash or a QEW/ONR wash. Sometimes I'll bring my jar of
Souveran just in case.
That pretty much covers anything I might want or need to do while away from home. My biggest concern are the bugs I pick up on longer trips so I like to get those washed off as soon as I arrive if possible. For windows the QD's or S&W do just fine while I'm gone.
Edit: One thing I forgot that
the other pc mentioned, a small piece of clay in a baggie. I haven't really needed it
yet, but I often show my buddies how to use it.