Creamery on 9th, or Brookers (which is block south of campus) for ice cream.
If you want cheap nostalgic lunch that is actually really good and has been hit up by BYU students and alum for years…go to Burgers Supreme north of campus or the original J Dawgs location this is on campus (well technically south east corner of campus)
BYU Book Store for the kids. In recent years they have actually make it pretty nice with great clothing and Knick knacks.
If you kids have interest in a specific major or field for when they go to college, (don’t know how old they are), you could take them to BYU buildings that house those majors. Tanner building for business, Eyring building for science, Fulton building for engineering, school of nursing building, Clark building for Law, etc.
If you are feeling adventurous and not in a rule following mood…Usually LES is locked up…but *sometimes* during the off season a gate will be open and you can technically get into the stadium and the bleachers to see the field. I would run the stairs there at LES for a workout from time to time as student.
Bean museum, bowling alley at the Wilk, Bell Tower
Kiwanis park (gigantic field and park) a block east of campus in the tree streets. Did lots of picnics there.