I sit the majority of the time. But a while back I think it was Carbonfiberboy that posted a video of Pantani standing for a long time during one of his races. I was impressed. I also noticed and think it may have been part of the discussion that Pantani was in the drops as he pedaled.

I'd previously always tried to stand holding on to the hoods or tops of the bars. And it seemed I didn't like that. However after seeing that video, I too found that for the times I do stand, holding on to the drops seems to make everything better about standing. It also uses some different muscles or at least a different range of motion for the muscles. And I still tend to think that the effort of standing uses energy just to stand that could be saved for pedaling. But for a last minute stab at staying on the bike when a grade briefly and suddenly pitches up to steep angle, I'll definitely use my last little bit of energy to stand as I gasp for air and try to get to where the grade lessens. Otherwise it's that walk of shame most of us don't want to do! <grin>

However it's still something I don't do enough of and need to practice. My cadence in the saddle while climbing is over 90 RPM until I start to run out of steam or run out of lower gear ratios. And at the moment I can't pedal more than about 65 maybe 70 RPM standing. So I have to actually slow down to stand up!