I've seen Good Charlotte over 100 times across the US, UK, Japan, and Canada. While some might consider that excessive, I can honestly say it was time well spent. GC shows are, above all else, a lot of fun.
You can expect to hear their hits, as well as a variety of songs from their five studio albums, though in recent years they've replaced early fan favorites, mostly from their self-titled album, with newer material. For the majority of concert goers attending a GC show, the entirety of the performance is spent dancing, singing, and jumping. So basically, for the most immersive experience, prepare to sweat.
Also you can expect to laugh. There is typically quite a bit of, what I like to refer to as, witty twin banter that takes place between brothers and frontmen Benji and Joel Madden. A Good Charlotte show is also a safe bet for families and younger fans, as there is usually little to no cursing or vulgarity.
Good Charlotte is currently on hiatus, but fear not, notable side projects from bassist Paul Thomas and drummer Dean Butterworth (The Strayed), Benji and Joel (The Madden Brothers), and, for the art fans, guitarist Billy Martin's comic book endeavor (Vitriol the Hunter) should keep fans of the talented quintet occupied for the time being.
If you are not currently a fan, I would suggest sampling each of the five releases: Good Charlotte, The Young and The Hopeless, The Chronicles of Life and Death, Good Morning Revival, and Cardiology, as they are all unique records and there is definitely something for everyone amongst their massive discography. In closing, to quote Benji "See you at the show!"