In reply to j0ntyg:
> No guidebooks suggest the gear you should take.
That may be true of UK guidebooks, but not of guidebooks universally. I've hit many guidebooks that will describe a "standard rack" for the area, then if a climb needs something different or special, describe what the supplement is.
On the topic:
I went after a local (Ottawa, Canada) 4-pitch climb called "Club Sandwich" at The Weir earlier this spring. I'd looked at it a few times, the first pitch takes some small stuff, to a ledge. Then a steep ramp with a crack along the back of it, to another ledge; a traverse across the ledge; then up a final corner. All looked good, so I took my usual rack (which goes up to a C4 #4), leaving my (old style) Camalot #5 behind. On the first pitch, most of the placements were wet, making the gear less than trustworthy, but not much I could do about that. Get part way up the second pitch, to where the ramp starts, and find that it is wide enough to get my shoulder into much of the way, with narrower bits. And the ramp itself is all glassy edges sloping the wrong way. 8m of squirming, past 3 placements for the #5 before I have to pull the hardest move so far out of the crack on a knee-jam. Finally, gear. Damn, I wish I'd brought my #5.