My wife is a (happy) nurse and I have had many late night career discussions with her so I know a thing or two. First and foremost, an associate's degree as the only degree needed to get a good nursing job is on the way to extinction. I am not sure where you are, but in Baltimore (shockingly large amount of prestigious hospitals), a BSN is the minimum education needed to get an RN job. Sure, there are still county and rural hospitals that accept AA's, but the pay is 20% lower at least. I know that isn't what you want to hear, but your parents, especially as nurse managers, are the exception, not the rule right now.
In the same mold as RNs now needing a BSN instead of just an AA, many of the highly sought after NP Programs are now transitioning to Doctoral degrees instead of the Masters programs that used to be required. Simply put, there is a zero percent chance that you can even get into an NP program without a Bachelor's.
Now, in regards to the salary difference I mentioned previously. Again, this is completely dependent on the hospital and the area. My wife's salary (3rd year BSN, RN) is $66,000 for 36 hour weeks. This includes diff and night pay. She works in a PICU so her skills are highly specialized and they obviously pay more for that, but a similar RN position at a rural county hospital that only requires an AA might start at $45,000 tops. She has recently been offered a Clinical Leader position (one step below manager) and the pay increase is roughly $20,000. Her manager easily clears $100,000 but her hospital requires a Master's for that position.
Feel free to ask me any specific questions and I can relay them to her. She has a pretty good handle on the educational scene because she teaches clinicals at her alma mater.