Depends.. Do you want to just 'get there' or do you want to take a 'scenic route'?
With 4 days on budget, you can probably do a little bit of both..
But, just saying between "So-Cal to Oregon" isn't much to go on... With that info, take I-5 until you have to go West or East..
I've done several trips between Washington State and Disneyland and driving I-5 the whole way (no RV in tow)... Get there in 2 long days of driving with one overnight stay around Sacramento..
Google Maps is a good guide too.. Just plug in your starting point and destination and it'll give you different options.
Good luck!
Mitch
