Personally, bringing amp head is a bit overkill (in fact, I don't own one!) unless you're really anal about the tone or unless it's your full concert or something. Also make sure you're driving if you wanna bring that...heck, can even bring a few guitars if that's the case *lol* Cos usually we seldom get the luxury of a customised rig and other bands are playing using the same rig as well, wouldn't be advisable to waste time to set it up and trouble the soundman on the settings, etc too.
For me, I just bring the guitar, pedal case, wireless system, extra packs of strings, some tools like allen key, string winder, extra cables/patch cables, a few multi-purpose adaptors, and a cloth to wipe my sweat-drenched guitar after the gig :lol: