Geocaching is a conduit to so much fun, so definitely keep that one up. When I first moved to SFBA it was the top activity that led me to discovering awesome places to return to. It's an excuse to get out with friends, and at the same time an activity to do when you're already out with friends, or solo, on a first date, or when you're watching your nieces and nephews.
Photography is another hobby that helped me find cool places. The wikishootme site shows places that need CC licensed photos, in case you need a photography sidequest goal. https://meta.m.wikimedia.org/wiki/WikiShootMe
Taking geotagged pictures wherever you go also lets you see where you have been on a map, and also where you have not been, which can give you ideas for new places to explore. Use an interval timer to make sure you take photos every N minutes while you're out, then look back on what you did. Or have everybody in the group photograph the same thing, then see how different people used perspective.
If you're in an area with lots of shops, spend at least 2 minutes in every single shop on the block, no exceptions.
I love The Book of Questions for conversation starters, so that's always good to have handy. Take it out with you on a walk with friends. Also if you have a flipper zero there's a questions app that is similar.
I keep kites in my trunk, because if it's ever windy and you have nothing to do, you might as well fly a kite. I also keep a picnic blanket in my trunk too, for spontaneous picnics and park naps.
Find or make a list of parks in your area and visit every one of them. Same for other geographical things you maybe interested in, like lakes, book stores, ramen restaurants, hilltops.
Have your whole group each make an alter ego and spend an hour or afternoon getting to know each other's alter egos. Explore personality traits that your real personality doesn't have.