Ahhh, I've travelled that way many times.
There is no "right way" to do a road trip this long. But here are some things you can try to make the trip more pleasant and even fun.
You can leave at 4 am, drive past LA (and any morning traffic) and make your first stop a breakfast break.
Along the way, stop at truck stops that have a fast food restaurant connected. That way you can get gas, eat and use the restrooms, all in one stop.
We like to stop at Costco along the way. Cheap gas, food court, big clean bathrooms and you can buy chips or something to snack on in the car.
I prefer driving 99 instead of I-5. Better pavement, the road seemed wider, too. There are fewer trucks, more small towns along the way and the route is only a few miles longer.
Take an ice chest with cold water, fruit, carrot stix, juice and milk.
With 4 kids, avoid making bathroom stops at small gas stations that only have one ladies and one mens room. Especially if there are other people in line, you could spend a half hour just waiting to use the facilities.
We used to like stopping at a park to eat the picnic lunch I'd pack the night before. Kids could play, adults walk and stretch. Bring a ball and frisbee.
Be careful about stopping at McDonalds with play areas. My kids loved these but it's easy to pick up germs and come down sick on vacation.
Sometimes we'd make a longer stop along the way to spend a couple hours in a museum or to sight see. That makes the road trip seem more like a part of the vacation, not just a miserable 20 hours in the car to get there.
Some places we've stopped on our way from SoCal to Oregon/Washington:
Sacramento. Railroad museum and the Old Town boardwalk are fun.
Redding. Walk across the bridge. See Turtle Bay museum. Take a walk along the river.
The Travelodge in Redding is older but clean and inexpensive. This is where we've stayed many times going back and forth from Oregon to SoCal. They have rooms with kitchens. We used to ask for the Sleepy Bear Suite which had beds for 6 and used to be under $100, as long as 2 kids are small enough to share a double bed. I've also gotten the kitchen suite and added rollaways for extra kids.
Portland. Tons to do and see. Or stop at one of the malls. We like staying at the Phoenix Inn across the street from Washington Square Mall. It's not fancy but has a pool and you can walk to the mall and shop or get something to eat. I think that's the mall with the lego store. Plus, no sales tax in Oregon. I prefer Bridgeport Village along I-5 which my kids call an old lady mall but there are a couple good restaurants there and some home decor stores.
When booking hotels, call the hotel itself, not the central reservation line. Ask if there's space for a rollaway in the room. We've also found some suite hotels like the Phoenix Inns have rooms with 2 queens and a sofa sleeper. They cost the same as a regular room, cheaper than having to get 2 rooms. Especially because some hotels are sticklers for allowing only 5 people in a 2 Q room for firecode.
If you plan on camping, try to find state campgrounds with yurts. Then you only need sleeping bags to stay, and won't need to pack tents and mattresses for 6.
Have fun!
