Your going to hit snow anyway you go so if I were you I'd watch the weather forecasts and make a break for it when you see a few days that look clear and bright. Before you go stop by Les Schawb and get some chains and a little block of instructions on how to put them on. I believe that Les will take them back if they are unused, but don't quote me on that as we never took ours back. Also have a good weather radio.
I've heard there are some real horror stories about taking I 84 in winter so I'd take 395 to I84 west and go south to I205 and then I5. I 5 shouldn't be bad except for the Siskiyou's and like the person said above, if you can get to 7 Feathers, its a great place to stuck at, and wait out any bad weather.
The I90 option to I 15 also an option, but I have no experience with I15 at all above Salt Lake City.
