Things to Do with Kids from Portland, or to Concord, Ca

Are you going Hwy 5? Go to the Schnitzer Museum in Eugene on the U of 0 campus. Best art museum between San Francisco and Seattle. It has an Asian collection that will dazzle your children's eyes and yours. Eugene has some fantastic health food stores like Sundance where you can buy a hot meal. Everything in Sundance is organic. Ashland has a lovely downtown and some fine playgrounds. Stop at Mt. Shasta which is a holy mountain to Native Americans. It is majestic. Shasta has an excellent health food store to get food at.
Castle Crag is across the highway from Mt. Shasta it is a magical set of rocks and caves to explore.
In Corning there is the Olive House where you can taste at least 50 different kinds of olives.
When you get to Concord Mt. Diablo is nearby and the hundreds of acres of interlocking county parks from Contra Costa to Berkeley.
If you go the SFO go to Chinatown and sample the DimSum.
I could go on and on but now many other Mom's who travel have given you the inside skivvy on where you can go.

Stop in Winston, OR and go to the Wildlife Safari....great drive thru animal park with a nice walk thru part which has a play area for the kids and a restaurant etc.

Winston animal park

Jacksonville

You have to get off i5 to go to Crater Lake or Oregon Caves
There is also Sea lion caves And bandon safari park if you take 101

If you're going to stop at the Jelly Belly Factory, you could also swing by Old Sacramento. There is a pretty good sized railroad museum with actual engines, a one room school house, the Delta King riverboat, and some really great restuarants.

There's a great hands-on science museum in Ashland called ScienceWorks. I haven't been there, but I hear it's great for kids.

You might look into the activities around Mt. Shasta and Shasta Lake. Right off of I-5.

Depending on the age of your kids, the Oregon vortex near the OR/CA border is really neat. I loved stopping there on our road trips when I was young. If you want to have a huge serving of the best ice cream ever, stop in Rice Hill, OR (south of Roseburg). I think it's exit 148 or something, but it's just a huge trailer that's famous for serving Umpqua ice cream--they even have their own website, they're so popular (just know that there are no rest rooms there, but there are tons of the other side of I-5!). We always try to time our drives so we can stop--yum!