Best route to Boulder Co. from Tacoma Wa.

Unfortunately you have a tough time that time of year. Mountains to the east and to the south. Watch the weather and pick a day to get through the mountains from Medford and Grant's Pass to California. Chains technically have to be on board but a good weather day will get you through and then cut across from the south on 40 and back north on 25 if weather cooperates. Perhaps others who drive that all the time no better than I but winter time in the the central and northern rockies and others can mean chains or wait. Good luck. On my winter trips from LA to Wisconsin I have had to go as far south as the 10 to avoid mountain weather and other years have come across on the 40 with clear roads.