I'm not sure which part of the country you are living in, but you will definitely make more money as a NP than as an RN in the majority of states. I live in South Texas and I'm making close to 100K per year. The most I could possibly make (without differentials) is $26 per hour as a R.N.
I'm board certified in 3 different specialties, FNP, ANP & GNP. The BON in Texas is very strict about NP's practicing within their scope, so don't assume that you can work in the hospital or in a specialty clinic if you're a FNP. The Board of Nursing says that you CAN'T! Fortunately, my ANP program included clinical time in the hospital, so I can practice there, but not in ICU (only Acute Care NP's can practice there). I'm also allowed to work in the various specialties, including urology, cardiology, etc. A FNP can ONLY practice in a primary care clinic.
Specialty NP's command more pay than the generic FNP's, except in Women's Health. If you want to practice in any specialty, ER, OR, psych, etc, then you need to become a P.A. b/c it will take you forever to get board certified in each of those specialties. That's the only problem I've had with being a NP, otherwise I love it and I get far more respect than I ever did as a R.N.