Initially, we after schooled for "enrichment" - we went on nature walks, talked about bugs and birds, played a ton of sports, did science experiments, learned 2 new languages, did "math lab" activities, read a lot of classics, played word games, did some computer programming, studied multiple musical instruments, watched children's plays, spent weekends in museums etc etc. Though it was fun and enriching, it was not what my son needed. He gets a lot of those things at his school already and I felt that my approach was chaotic and without direction.
We have switched to the the "deep learning" track - the "Not Many things, but go Much Deeper into a few things" track. We restrict ourselves to 3-4 areas and delve very deeply. This method of learning is more suited to my son's interests than a "salad bar" style approach.
If your kids are up to structured after schooling, you should start with their areas of weakness in school and try to shore it up. If they are globally gifted and have no weaknesses, you can try doing advanced academics. For me, a curriculum and a simple lesson plan for what I will do on a weekly basis helps me keep on track. Math is a good area to spend time on and so is a foreign language if their school does not offer it. Computer programming and music also take up a fair bit of afterschool time for my son.
