First of all, very few docs, FP or otherwise, earn a "salary". They have "income", which means that the more patients you see, the more you make. "Salary" is a set amount of money paid to you by an employer, and it drives a lot of docs nuts to have it referred to that way.
With that said, your income as an FP depends almost entirely on one thing: who is paying the bill . If it is private insurance, you will make 200+ working 8-5, 4 days a week. If it is largely Medicaid, Medicare (as many, but not all, rural and poor urban areas are), you will make much less. If it is the VA, or the IHS, you can expect to make 120 or so with none of the hassles of running a business or getting sued. That likely has some loan payback on top of it, if you are a new grad.
Here are two cases I can illustrate, both from docs I know personally (on West coast):
Doc #1 takes mostly private insurance, including a good portion of his income from capitated or other HMOs. Takes home over 200k, works 4 days a week, takes a 2 hour lunch, and only works 8-5 because he gave up his hospital privs (too much hassle). Oh, and it is a suburban-almost-rural type practice.
Doc #2 has a rural practice, also works 4 days a week, but has slightly longer hours (7-6), because he has to make rounds at the hospital before and after work, which take about an hour each. Takes a 1 hour lunch. Patients are about 40% Medicaid/care, 50% private insurance, and (I'm guessing) about 10% deadbeats (poor folks who haven't had the gumption to file for Medicaid, and don't pay). Has been slowly seeing his take-home dwindle to about 100k as Medicaid pays about 50 cents on the dollar, and paperwork hassles have forced the practice to hire new grunts to deal with it. But, he still loves his work and is an excellent doc.
Last year, this doc sold his practice to the local hospital, which happens to be a Medicaid sponsored hospital, which means that Medicaid will now pay 100% of the bill (instead of 50%, as above, I hope that made sense). So he became an employee of the hospital on "incentive" (different from "salary" in that the more you work the more you make). Rumor has it that he makes significantly more now, although I'm not sure what that is. I know he was pretty pissed about making only 100k, though.