I save most things in a private Google map. In the rare case that a museum, restaurant, hike, etc isn’t listed on Google maps, you can add a pin to the map and make notes for your private map. Seeing all the things I might want to do on a map helps plan an itinerary. Also, you always have handy access to things to do, see, visit if you take an impromptu trip somewhere. For a planned trip, I add notes of major attractions to my itinerary in Tripit.