I don't know which packs you have and I'm not too familiar with the NSB rules, so not all of this may be possible. ;
But here are some of my suggestions:
- If applicable: A study group where they do homework together. Not super interesting, but it gets some of the workload done while still getting outside (just pick a location other than their house ofc) and seeing their friends.
- Maybe something more along the lines of a private disco? Singing, dancing, maybe getting drinks / snacks.
- Or for giggles, a club that's basically a tropey "girls' night": spa activities / yoga, trying on outfits, chatting (friendly socials), watching movies, eating popcorn
- A book club - reading, discussing books (friendly socials), drinking coffee
- Something artsy? You can mix activities like playing instruments, crafting and painting or make a club focusing on just one
- A sports club: bowling, snowboarding, basketball, darts, swimming, rock climbing, etc
- A chess club while we're at it
- Or maybe an even nerdier one - chess, reading, doing research, using a telescope, debate, programming, using science objects, etc
- If your Sim isn't too much of a couch potato, maybe an outdoorsy club - fishing, hiking, campfires, cloudgazing / stargazing, looking for frogs, etc
- Or an eco friendly one if they care a lot about the environment: gardening, conservation activities, caring for animals, etc
-You could also do something pub / bar related: mixing / having drinks, playing foosball / pub games, etc
- There are plenty of games your Sim can play with others that aren't video games: foosball, cards, don't wake the llama, etc
- If you don't mind one with a goofy theme, a Grilled Cheese club is always an option. :D
You could also make a seasonal club if you don't mind updating the activities regularly:
- Spring: gardening, cleaning (you know, spring cleaning lol), working out (for that summer body), spring activities in general
- Summer: drinks, using the lawn water slide, swimming, cloudgazing / stargazing, fishing, summer activities in general
- Fall: cooking, eating (duh), campfires, scaring (if they are in that Spooky Day mood), fall activities in general
- Winter: baking, skating, skiing, snowboarding, winter activities in general
There's probably plenty more buuut it's already pretty long :D