These online maps are now ready for almost all of the national forests in California, Oregon and Washington. Here are the links:
http://www.mappingsupport.com/p/gmap4_usfs_maps.html
Please read the Tips. There is a link to the tips in the upper left corner of each map.
To the best of my knowledge these are the only free online maps that show trail mileages without making you click anything.
They are also the only online maps that let you see the forest service roads that are open and roads that are closed by toggling those layers on and off.