Our family has done a few different trail rides in different locations. The Maui Mountain Activities was one of the better ones for two reasons. First, the scenery is spectacular and varied, and second, the trail guides were top notch and extremely knowledgeable.
We met at a small parking area / field a few miles outside of Waihee-Waiehu. A van shuttled us to the corral, which was stocked with over 20 horses, all of which were in good shape and well-trained for trail riding. None of the horses caused any trouble the entire time we were riding (aside from trying to eat the plants along the trail).
The outfit is fairly new, and they mentioned that they were still building up their services. However, they did have everything we needed -- helmets of different sizes, saddlebags for water bottles and such, and a step stool to help people onto and off of the horses. The corral also had a number of peacocks, some sheep, a dog (to watch the sheep, I guess), and portable bathrooms.
We started up the trail going uphill through the lush forest. The trail guides knew all about the area and the different kinds of plants we saw. They were also very experienced horsemen. The uphill trail had two stops. At the first stop, we had a great view of the north coast of Maui to the east. At the second stop, we looked into a steep tropical valley with some distant waterfalls. After going uphill for about 45 minutes, we went down by a different route to the sea shore. We could not go down to the beach, which was quite rocky, but we got right up to the edge of a seaside cliff. Throughout the trip, the terrain was constantly changing, which gave additional interest to the journey.
Probably the best part of the trip was that they allowed us to let the horses trot from time to time, and at the end, we were able to let them run at a good lope. I don't know enough about horseback riding to be able to do this well, but it was fun to try it for a couple hundred meters. This part was strictly voluntary.
Overall, it was a great trip, suitable for people of all ages. I highly recommend it.
One word of caution, which some other reviewers also mentioned. If it has not rained for a while, the trail can be quite dusty. You may want to bring a bandana to cover your face. The trail guides do a good job of minimizing the dust to the extent possible. Nevertheless, you and your clothes will also get a bit dusty, so if you plan to do anything after the trip (like go out to lunch), you may consider bringing a change of clothes, too.