Unlike most other monuments in Delhi, red fort is comparatively less crowded... COMPARATIVELY!
A monument with Historic importance can be a good adventure trip for the young ones. But for that, make sure you read some bit of a history before you take them there, so that the tour becomes great fun. The old style building structures, the huge lay outs, various chambers and their uses will all be a lot of fun to explore. There's a huge park area where you can spend some time to rest or play running games with your kids. The area is huge so kids will enjoy outdoor games there.
Washrooms are again a concern. However, the place is so huge, that it looks moderately clean. You can also coach your children on what not to do with these monuments lol.
I love to take our family visitors with kids to red fort as it becomes a fun spot for them to see.
Child friendliness: 3/5
Adventure Quotient: 4/5