The Henderson Waves bridge is part of the Southern Ridges trail that is 9km long. As Singapore's weather is humid, it may be a little hard going to go all the way with kids. So you can focus on either end of the trail. The Henderson Waves side is close to Mt Faber, which offers great views of the island. Alternatively, you can start from the other end and walk on the canopy trail and hill top walk, walking amongst the tropical secondary forest foliage and spotting birds along the way. The latter trail is also close to Gilman village, which has some nice art galleries and restaurants.