Do you climb standing or sitting?
Just as a throw in. The MTB community (press mostly) think that full suspension mountain bikes are much more effecient because the suspension allows the rider to spend more time in the saddle and less time standing. Now this may be obvious when discussing rough or loose terrain but they also claim that climbing hills is easier while sitting. This is the basis of the premis that a 30lb full suspension bike can be more effecient than a 25 lb hardtail with front suspension only.
2nd throw in. TDF riders appear to get out of the saddle for short bursts of power (or as reported to stretch muscles in a different way) but soon return to the sitting position to spin on up the hill. The idea here is that standing is powerful but consumes a great deal more energy than sitting.