OldChum
Here's the web address for Consumer Energy Information: EREC Reference Briefs on "Log Homes and Energy Efficiency" from the U.S. Department of Energy;
http://www.eren.doe.gov/consumerinfo/refbriefs/ca8.html

As far as log homes in Washington State go, if you have good Southern exposure to the sun you should be in good shape. Logs store the heat from the sun like a "Thermal Battery" during the day and release the heat during the night when you most want it; During the evening they cool after the heat has been released keeping afternoon temps cooler inside the home.
The R-Value of a log is generally pretty poor and log homes fair differently depending on climate zones and Southern exposure. Generally they fair pretty well here in Washington.

How badly have the logs checked "cracked" in the home your looking at and have you checked it for air leakage? Easy to do "checking for air leakage", take a lighter, especially around the inside corners, and watch the flame.

E-Mail me if you'd like, with any other questions. I am currently building a log home of my own and have done tons of research on the subject.