"My predominant feeling is one of gratitude. I have loved and been loved;I have been given much and I have given something in return...Above all, I have been a sentient being, a thinking animal, on this beautiful planet, and that in itself has been an enormous privilege and an adventure." O. Sacks
We have some really great short, steep hills on one road here and on short rides I'll stand the whole time because I like doing that better, but long hills are definitely spin-all-the-way. Sometimes to finish it off standing is nice, but usually I'm just too tired. Climbing is definitely one of those "do what feels best" things. I think I just like passing my friends on hills when I stand.
Word of advice though- even though it uses up a little more oxygen- if your lungs are in good enough shape singing always gets me up hills faster. Helps if you're in the country and no one is around so you can't be self-conscious, but find a couple songs you know all the way through and see if you can sing them on the hills. It's a great feeling when you get to the top of a really huge climb and get to belt it out on the descent (please tell me I'm not alone on this).