Who you should get to write your letters of recommendation is certainly a subjective topic. I was recently accepted with letters from a CRNA, an ER physician, and a former nursing school professor. I picked these individuals because each could attest to me as a professional on different levels. I had a buddy who decided to use 3 physicians for his application.... I can't say that this was wrong as it was his choice. From my research, it seems that CRNA schools want well-rounded individuals who are both team players and who can function independently. I've also heard that some schools don't weigh the letters that heavily, so take it all with a grain of salt.