I'm not sure if it will be directly relevant to your questions regarding care during the birthing process, but I think with regard to patient satisfaction/experience a good place to start is the Hospital Consumer Assessment of Hospital Providers and Systems (HCAHPS) survey. It's made available by CMS and you can get a sample of the survey on the link. Best of luck in your pursuit.
I have 32 years of experience. I suggest that you have them rate their experience 1 to 10, and then write comments that you read. i think a scale will give you less information, not more. Using a scale would be comparable to when , you go to the doctor and you get every kind of care except the doctor looking at you and asking : How are you? If you use a scale , you are doing the same thing. Each person is different and will give you a different answer. By asking for comments, you can pick that up. By using a scale, you are mainstreaming all people into having similar reactions. wont be accurate.
Another suggestion is reading the book THINKING FAST AND SLOW by Kahneman, But reading the book, will tell you what i wrote above.