I do stand some when climbing hills, particularly on a mountain bike on trail, road bike with higher gearing, or on a bike with limited gear range. I don't stand much when touring or riding around town with heavier loads, trailers, or kids due to side to side motion when standing. I gear down and spin. Also, proper saddle height and position fore/aft keep me less likely to stand while climbing. How well the saddle fits you, it's height, and the overall fit of the bike also contribute to comfort and efficiency or lack thereof. I set my saddle so that my knees are nearly fully extended at the downstroke of the pedal. I ride as light as possible in the saddle with a a balance of my weight on the pedals, saddle, handlebars. I tell my kids to not sit on the seat but to ride in the saddle of their bikes. They tend to want to sit with their weight on the seat of their bikes with the saddle position too low when still inexperienced. Once they get it, they are better riders and more comfortable as well. When touring, we can cover 40-60 miles per day if needed with all 4 of our kiddos, now ages 5-15.
I prefer a hard leather saddle, properly adjusted, and regular shorts or pants. Don't really have a problem with saddle sores even when covering up to 75 miles a day in town, long days in the saddle when touring, or even longer days in the saddle riding pedicabs. I had more saddle sores, ingrown hairs, pimples, etc., caused by bacteria as described by fietsbob, many years ago when I rode in synthetic bike shorts with padding, padded saddle, etc. I much prefer cotton or non-cycling specific pants, shorts, swimsuit, whatever, on my old Brooks saddles. Lets things breathe.