Also, some bikes are just easier to stand on than others. I can stand forever on my new cruiser bike; I guess because of the geometry being very laid back, and with only one gear, you can't sit and spin whenever the road points up, even a little. When I used to have a Terry Isis with a 24" front wheel, 700c in back and very short stem, I had a terrible time standing; I guess the small front wheel combined with the short stem made the front end very squirrely in its handling. I have the same issue with my Bike Friday with 20" wheels now. It also has a short stem, so not sure how much of the problem is the stem vs. the wheel size; I assume a combination of both. I do much better on my Trek with 700c wheels and a normal-length stem, but I still don't stand all that often.

I am definitely more like you, Crankin, shifting and spinning wherever possible, but sometimes I will stand if I just need that little extra "umph" to get over a short hill -- so long as I am not too tired. Once I'm too tired, I can't bring myself to stand, as it definitely takes more energy.