I was just wondering what everyone else tends to do. I find that I am a more effective climber while I am standing and can seemingly go on forever when I get a good pace going. The group I ride with likes to try and find as many hills as possible and everyone is always sitting. I also noticed that it seems that every time you see Lance Armstrong climbing he stands more than everyone else also. Obviously this is where our similarities stop! 
This is a really good question. I would say that I’m more effecient in the saddle when I’m climbing. I too try to stay in my saddle as much as possible. I would think I expend much less energy when I’m in the saddle.
I stand to stretch my legs, rest my butt or fart.
One of the benefits of the cut outs that a lot of new ergonmic saddles is that you do not need to stand up to fart. The rear coutout on the Body geometry saddles works well.
Standing up involves a bunch more muscles and has a corresponding effect on heart rate. From a purely cycling standpoint, sometimes you just have to get up and go when racing or riding in group. From a triathlon standpoint, you should keep your behind planted and stay on the aerobars for everything but the really steep hills. Sitting up then doesn’t hurt you aerodynamically and rests your neck a little. Standing to rest your behind is fine, but do not get up out of the seat to attack a short hill.
This reasoning is based off a year of riding with a power meter. Standing on a hill creates a huge power spike, sometimes as much as double your normal average power. That doesn’t make for good fuel enconomy.
Even if you are not standing, most people ride short hills way too hard. I’ve experienced this at every hilly race since I bought the power meter. I will be gaining on someone and pass then only to have them go hammering by me up a hill either in or out of the saddle. I keep my spin up and gear way down and they roll away from me. Near the crest they eventually sit down and the gap immediately narrows. By the time we roll over the other side I always blow by them. If they stay away from me early on, at least half of them come back to me by the end of the ride and then even more on the run. I caught every rider in my age group that passed me on the bike last Sunday at Powerman North Carolina.
Just food for thought.
Chad
In fact I believe the technical term for the cutouts is “Fart Channel”, no?
I also tend to stand more than most of the people I’ve ridden and raced with. It just works for me. My breathing AND pulse drop at the same speed when I stand. I just guess I’m wierd.
Sitting = more efficient
Standing = more effective
It depends what you are going after…and how long you plan on sustaining it.