Re: easy travel routes
I have traveled both ways and with either one you could have some bad roads, but the I-15 route is your better bet. The distance by I-80 is 840 miles and by I-15 it is 800 so the difference isn't that much. But by traveling via US99 to Bakersfield, then over CA58 over Tehachapi Pass and through Barstow to I-15 will keep you south much longer and the only pass will be one that don't get snow. I-80 could be bad at almost any point in the trip.
Traveling either way, make sure that you keep a close eye on the weather and sit it out if you should get a bad storm. Traveling I-15 you should be pretty clear of snow until you get to St. George or even Cedar City. Also, Donner Pass will be more of a climb than Tehachapi, although neither is that big a deal.