I'm not a rock climber, but rock climbers do seem to love the wilderness. It has no lack of rock faces and interesting little features.
If you try canoeing in the Sipsey Wilderness, let me suggest going when there's plenty of water. Our little canoe trip turned more into a soggy hiking trip when we tried to go in a dryer period.
Favorite thing: Generally, not all of the Sipsey Wilderness's star attractions are on the well-worn trail. If you get off the trail and explore a little bit with the map, you'll probably be well rewarded. If you're at the top, do be careful not to walk off a cliff. There are plenty in Sipsey. (Bushwhack at your own risk).