You may find it beneficial to post the age of your swimmer and what level they progressed to in the rec program (i.e. in CS, there are beginner levels for younger students <5 or levels 1-6 for older students IIRC). Our children learned through the CS program through level 6 and we found that they progressed fastest when we spent some time at the pool every week practicing. Some instructors were definitely more adept with certain age groups. Some of the instructors also taught privately, but that was a long time ago and I don't know if the parks dept still lets them do that. It definitely helped when there was a particular skill that one of my kiddos couldn't quite get the hang of.
A lot of parents use the coach at TruFit, and I will try and ask for a few names from my friends whose children are still swimming/learning.