Sounds like fun! For big and small.

On my various trips to Lima and around Peru, saw lots of kids in that range. (Maybe 3 is on the low end of things.)

2 things I recall.
- Overflight of Nazca lines. Shared plane with family with 2 boys. They screamed their heads off in excitement.
- Vistadome train ride to MP. There was a kid that was a real rail fan. Could tell us what the train was doing, the various rail signals, sidings, etc. Was about 10 to 12.

Have fun,
SF