I think RN to PA isn't a good way to go. Nursing and medical are two different things so I think it is pretty silly going from one model of care to another. I know this personally because when I started RN school that is what I was going to do but nursing (RN) focuses on the clients and their perception on what is going on while the medical model goes for diagnosing what is physically wrong. I think if you want to be an RN go for NP (unless you have problems with the nursing model). That is just my 2 cents though. You will learn a lot of medical things through nursing but personally it isn't the best route (I think).
If you want to go for a PA biology is a good route Medical tech. is even better. Because both focus on the biology of the human.
North Dakota is the only one (to the best of my knowledge) that requires an RN first. There are lost of RNs in PA school. Generally you need to fill the prereqs and many won't give credit for courses within the program-- in other words, everyone who gets into the program takes all the classes.
Thanks to all who replied. I'm from central Mississippi, so I can't really see going anywhere near the Dakota's. I also can't see myself doing the NP thing. I think I'd enjoy being a PA after i get my BSN, might try for surgery.