I think it depends on what state you are in, and probably differs from city to city even. Also, there are shift differentials. You will get paid more working nights vs. days, or evenings. You also get paid more on weekends. At least where I work this is how it works. I work on-call, so I get paid more, but do not have the option of having medical insurance through work. Also, I get called off more than someone with an FTE, and I get floated first. I make between $25-$30/hr. I have been an ob/gyn RN for 8 years. I'm not sure about L&D. Also, agencies pay more, and you get a lot of experience. I work for an agency as well and really like it. The down side again is getting called off at the last minute, or being sent home before the shift is over because the census went down. I have made about $40/hr working for an agency. They are actually lowering the pay now, but I think it will still be a little higher than a hospital would pay. Most agencies like you to have at least 1 year of experience in a field. It is a little scary going to a hospital where you don't know anyone, also, you don't know the protocols of that particular institution. Luckily, I have had wonderful experiences where I have gone. Good luck, I hope this helps.
I am in southern California. I make $34 plus NOC shift differential of a little over $4 more an hour as a per diem employee. I don't get called off too much because they don't have enough staff to make me truly 'extra'. I have less than a year of experience, but all per diem employees are paid the same. I think the average salaries for full or part time employees around here are about $23-$30 an hour depending on experience. Not too many hospitals in my area pay a weekend diffrerential--wish they did!