Wachusett is overall a good learning and family mountain. Smith Walton and 10th offer a decent challenge but by and large the strength of this mountain is in it's green and blue trails.
The downside is the crowds. Ski midweek or do a half day mornings because many trails become icy, including the blue trails by early afternoon.
I took my kids to lessons there and wasn't impressed. One of the instructors was good but the kids weren't assessed correctly and hence it wasn't worth it.