As for timing:
- I believe season now runs from November to March, which is probably longer than it once was because of global warming. Tours that fly across the Drake don't start until late November or December to ensure the landing strip is ice-free.
- My coworker said that a big upside to going later in the season is that you'll see new penguin chicks.
- December and January is high season, but my guess that's probably due the holidays and people having time off. Coming from the northern hemisphere, you're budgeting minimum 2 weeks for the trip, so many non-retired travelers would want to take advantage.