Remember, a national park is not a zoo. These animals shouldn't get up close and personal with people. They become too dependent on human handouts and foods. Of course, that's exactly what you want to do in bear country. Talk or sing as you hike, or take a walking stick with bells.
Bears typically go away if they hear people.
Even if you're planning a short day hike, stash a first-aid kit, flashlight and waterproof matches in your day pack, along with water for everyone and plenty of healthy snacks. Don't leave the trailhead without jackets for everyone. The weather can change quickly. Count the constellations. No matter what their age, the kids will hate rushing from waterfall to scenic vista.