I go up to Northwestern Oregon at least 4 times a year and always ride logging roads as they cultivate trees on a large scale--it is very safe, you can always ear the trucks coming and usually they are logging in a particular area--so you know where they are.
A good fully suspended MTB is what is needed, I have had over the years used no suspension, only front and now fully suspended and it is the best by far not only for relative comfort, but mainly for traction and control. I never tried a 29, not sure it adds anything?
Lots of wildlife as well as bears, dear, elks etc. and other animals have adapted--of sorts!
Northern Michigan is much the same. I ride the logging roads on a Trek DS. Logging seems to have made a comeback up in the U.P. Not many "main" roads, all two lanes though some have climbing passing lanes to avoid tourist backups I guess. Nothing like having a tandem log hauler pass you at 55-60 mph when your riding the shoulder.
