http://www.kiplinger.com/tools/bestcities_sort/index.php?sor...
For example, note that Honolulu has a salary coefficient of 92, but it's actually one of the most expensive places in the country to live. It has a cost of living coefficent of 171.
Another thing is that in addition to cost of living, one must consider state taxes, which you can calculate here:
http://letsrebuildit.com/index.php?option=com_jumi&filei...
WA, NV, TX, FL, and IL have very low state taxes (for me), whereas DC, CA, HI, NC, and NY have high state taxes.
I've also been in the situation working for a remote employee who tried to pay comparable CA wages (wasn't in the Bay Area), but didn't understand the true cost of living differences. Also been on the flip side, in office in SF and looking for people in cheaper markets.
On the other hand, top developers can pretty much ask what they want no matter where they are working from.