A lot of good suggestions here! Are you celebrating anything in particular? We wore our anniversary buttons when we went for our 7th anniversary and got lots of free pixie dust: free desserts, serenaded by the Dapper Dans and others, special character interactions, etc. That definitely made our trip special!
For a regular family trip, though, some free pixie dust can be found by staying in Magic Kingdom for the Kiss Goodnight or riding certain outdoor attractions during Wishes (the view from Splash Mountain, Seven Dwarfs Mine Train, or the Astro Orbiter is especially amazing). One of my most magical memories was riding the monorail around Seven Seas Lagoon and passing Magic Kingdom during Wishes. In Epcot you could try eating around the world and trying a special snack in each pavilion, which is a fun and relatively inexpensive treat. In Hollywood Studios you could become Honorary Citizens of Hollywood at Walt Disney: One Man's Dream, which doesn't cost anything. I agree with the others who have said trying to finish the Kitchen Sink at Beaches & Cream would be a fun group activity, a shopping trip to Disney Springs, or maybe a pedicure at Senses Spa. It really depends on the people you're traveling with and what they're interested in, but there are definitely ways to make a trip memorable for everyone!