Learning and development, anywhere, is primarily depending on the individual. Second, resources, i.e., what your hospital or clinic can provide for professional development. There are PT's who do the bare minimum under the resources they're provided, and there are those who pay out of pocket to satisfy their interests.
I think it depends on the SNF. If you're going to be the sole PT supervising 6 PTAs, that's obviously not an environment to seek. Another red flag is having a staff of new grads or therapists with < 2 years' experience. Run. If it's a SNF with a healthy mix of baby PTs and seasoned therapists, that might be a better place as a new grad. No matter the setting, you don't want to be in a vacuum. The ideal situation is someplace where you'll have some type of formal or informal mentoring/guidance. Unfortunately that's difficult to know unless you've done a clinical rotation there or know someone who's worked there.