Island Lake is a great place to take someone who is not an experienced backpacker because the trek is not too hard, the temperatures are cool and the scenery is amazing!
You begin at the Crystal Lake trailhead off of the Mirror Lake Highway. On the way to Island Lake you pass several other lakes including, Crystal Lake and Long Lake. The hike is not too hard but there are several switchbacks at the end to get you up above the ridge where the lake is located. It is a large lake and there is a trail that goes around the entire lake with campsites scattered around- particularly on the side with cliffs. There are also plenty of trees around the lake to hang hammocks from which is what we did.
There is fishing and cliff jumping that can be done here while taking in the beautiful scenery. If you arrive at the destination and if for some reason you decide that you would rather camp at a different lake, there are dozens of others within a few miles. That is one of the amazing things about the Uintas. Even on this relatively busy trail, you can find solitude if you want it- just find a less popular lake.