All of these hikes are good as long as you have enough other stuff to do to fill in the rest of the day so it's kind of a good-news/bad-news situation. The success or lack of it has generally hinged on how well we have complemented the hike with other activities.
Streaked Mt: Steep but short. Our girls are generally off the mountain by 1:00. Lake Pennesseewassee is a good swim choice and the Gem Mines are in the same area.
Douglas Mt: There's short and there's really short (this one is about 30 min each way max). There's a glass museum and Sebago Lake nearby. It probably needs one other thing to fill it out.
Sabbatus Mt: Kezar Lake is the major attraction nearby. There's also the sign that points to all the towns named after countries not far away. Still needs another activity,
Mt Tire'm: We've only run this one once in conjunction with an age group overnight so it's difficult to tell. My sense of it is that it's a creditable hike but like the others needs some other activities.
Bradbury Mt: This one has enough stuff around it to make it work. The hike is quite short but combined with visits to the Desert of Maine, the world's largest globe at the DeLorme store and a trip to the beach have filled up the day quite nicely.
Morse Mt: We've never tried this with younger girls and haven't explored what other possibilities are in the area for that reason. But it's easy enough that we might want to think about it.
Wolfe's Neck: Calling this a hike isn't entirely accurate. It's a great trip but we tend to walk the loop trail until we find a nice beach spot and then hang out and check out the marine life along the beach rather than complete the trail.
Mt Crag: This one is an exception to the needing-more-stuff rule partly because it's a longer hike and mostly because it's a longer drive. The drive can be tough on littlies but the trail has a turnstile and a cool view of Mt Washington and the cog railroad. The one thing it needs is a good swim spot which despite the presence of the Androscoggin River I have yet to find.