I stand all the time on climbs. It's fun! How many gears you shift up to make your lower cadence and increased leverage work will depend on your cassette. Usually a two-tooth difference for me, which works out to one shift on my antiquated 7-speed stuff, and two shifts on newer road cassettes with one-tooth jumps.
If you intend to do this in groups, make sure you practice your transitions so that you can do it smoothly and not cause the person behind to crash into you.
