My family of five recently stayed at the Big Rock Candy Mountain Resort in Marysvale, Utah. Located in a pretty remote area of the state just off of Highway 89, there's not a lot around this area of Utah - except for some fun outdoor activities including zip lining, ATV off road-ing, and river rafting. We didn't try any of these activities on this visit, but we plan to return in the future as they looked like lots of fun.
The resort isn't luxury, despite it's name. It is simple and clean and quiet. We stayed in the Hideaway Cabin with our family of five, as it can fit up to six, though six adults would be really tight. We have three kids (5, 6.5, and 8). You could do another small kid in there, but more than that and it would be tight. There are two rooms in the cabin. One with a relatively comfy king-size bed and a sofa that pulls out into a bed plus a TV with DVD player. We couldn't figure out how the satellite worked but it says it has DirecTV. There is a super low hanging ceiling fan to cool the air. The other room has another sofa bed, table with four chairs, kitchenette with microwave and fridge. There's also an air conditioner in that room that cools off the whole cabin decently. There's also a small bathroom with a shower, sink and toilet. It's all pretty basic, but does the job. The cabin has its own yard with grass, which my kids thought was a blast when they ran through the sprinkler for a fun cool off. There's also a little front patio with a table, chairs, small BBQ and a wooden chair. The trees provide nice shade to relax under.
For the $109 plus tax price tag, this cabin was a great deal and someplace I'd stay again. If you have a smaller party, there are some cabins right down by the river which I'd opt for instead.
There are ATV trails right outside the doors of the cabins which look like lots of fun. You can rent those from the resort's store. You can also catch guided and unguided river rafting adventures from the store. We thought about taking an unguided rafting adventure or tubing but the river was moving too quickly for us to feel comfortable with such young kids for their first trip, though they allow kids two and up. We saw several groups doing guided rafting trips through rapids. They looked like lots of fun. Down the road there is also zip-lining and a cool rock climbing-esque adventure to be had for kids and adults over 7 years old. Check out all of the available adventures at http://www.candymountainresort.com/