Aimee, I use a combination of tools and techniques. For one, the ITA Salary Survey has been really useful in calibrating my expectations by position type, experience level, and company size. I have also relied on PayScale to give me a good sense of ranges, Glassdoor as a secondary source for the data I am already gathering, and the Bureau of Labor Statistics for national averages.
I have also swallowed my discomfort around talking salaries and freely share mine with others to gauge their reactions and encourage sharing on their parts. This allows me to benchmark within my own network because increasingly others (especially women) share their actual ranges and earnings with me.