Well, Respiratory therapist can work as registry and per diem.
There is always in need of RT in hospitals, sleep centers, pharmaceuticals, schools
and subacutes. As for advancement its not a lot really. You can only get your Bachelor in RT and thats it. Since RT is already a specialty theres no more advancement unless you want to became a BSRT. As for nurses theres always advancement and you can always specialize in any areas. You can also work in so many fields like schools, offices, prison, county jobs, hospitals, nursing homes, urgent care, amusement park etc.
For the job RN have so much work compare to RT. You have to see the chart its like twice the size of a bible. Its thick and they have so many documentation to do. They do more patient care and they interact more with the doctors and patients family. They get the complaints!!! At the hospital where I work ( kaiser ) the RNs are always stress while RT just sit back and relax but when theres a code blue thats when we really get to do work! I am an RT and I love it. I get to be in different areas in the hospital everyday I dont get stucked on one floor. I get to go to ER, L&D ( labor and delivery), peds, NICU, ICU, CCU, DOU, med surg and of course respiratory department where we take out patients for Pulmonary test. RT also deals with a lot of math and physics and no poops hehehe. The pay for RT where I work is $30.00 an hr and for RN is $32.00. They also have RT registry at kaiser and they pay them $550 per 8 hr shift. Even if u stay only 7 hr or 6 u get paid $550. I dont like to work my butt off. I do like to work but not to the point where i get so stressed. Thats why I picked RT you get to sit down and you also get to work.
It really depends what you like and how stress do you want to be hehe.