Pennsic is one of those SCA places where you can literally be busy 24/7 and not get to everything. Here is just a list of a few of the highlights:
Fencing, fighting, archery, youth combat - everyday, all day, single, melee, different tournies, different shoots, war points, even some which support charitable causes....enough to make grown-ups beg for nap time.
Arts and Sciences classes - if you're interested there are probably half a dozen classes in your subject area, some hands-on. There are so many classes that you'll want to take a highlighter along just so you can spend hours reading about all of them and picking the ones you really really want...."but I want to take 11th century illumination and 14th century buttons and sundials, but they're all at 11 a.m. on Monday!!!"
Dancing - classes during the day and dances every night in the barn, with a few balls thrown in for good measure.
Shopping - shop til you drop, literally. There is enough shopping that you can spend two whole days just shopping and then hope that you've seen it all. What can you get? Fabric, yarn, jewelry, pottery, bows, swords, complete sets of clothing, herbs, shoes, books (at least until Rowena has been there :)), hats, furniture, tents, chain mail, armor, swords, musical instruments, and tons and tons more.
Talking - with 12,000 people on site, it's hard to not stop to talk every 50 feet.
Party! - every night, whether it's quiet get togethers, bardic with songs of all kinds until the wee hours, the Baronial party (which will probably be the middle Sunday), the Known World Party (at Midrealm Royal and open to the public), middle eastern dancing around the fire and lots of alcohol, or just a loud rowdy get drunk bash. Some parties are open to the public, just wander by and stop in, if in doubt, just ask, some are open only to groups. In the swamp, for the wild ones, just follow your ears to the sound of drums, yells, and large crowds. You can literally party from sundown to sun up.
Courts - want to see lots of pretty clothes and people touched because someone thought that they were worthy of an award enough to write them in, just stop in at one of the courts. Each kingdom usually has it's own court, and then there is an opening court and a closing court.
Touring - If you're new, take a tour. Some of the camps are really marvelous, from a cathedral with a stained glass window which is lit at night, to a hobbit hole as a gate, to a whole encampment of large striped Viking wedges. I've even seen multi-level Japanese pagoda tents. There is a wagon ride which you can take down around the lake which I recommend to everyone their first year.
Didn't see it here? It's probably still there, just ask and some of us who have lived there for years can help steer you in the right direction.
Baroness Moira MacGillavrey
Baronial Land Agent for Pennsic