Observe the California aqueduct. Along varied sections of I-5 you can see Governor Pat Brown's legacy slowly moving the water from the Sierras down through the farm towns and into the LA basin. It has a very long political legacy, so observe the glories of water politics in action.
Have lunch at Pea Soup Andersen's. Pea Soup Andersen's has two locations off of I-5: Santa Nella in the Northern area and Buellton further south. Depending on when you start your journey, Pea Soup Andersen's can make a great stop on the way and the food is hearty and good. Plus, you can take pictures and go to the gift shop to add a few T-shirts, snowglobes or canned soup to your carload.
Have a great steak at Harris Ranch. You'll recognize it by the smell of the cattle fields a few miles north, but Harris Ranch is a great stop on the way down I-5. It offers fresh steaks on its menu and you can also pick up a few things to eat once you've gotten to your southern destination.
Take a rest. Now, I-5 offers multiple rest areas (see Resources) to stretch your legs and rest your eyes. There's public restrooms, pet areas and services for RVs at most stops. Buttonwillow is a particular favorite spot as its a good midway point on the drive south.
Head over the Grapevine. Just before you enter the LA basin, you have to head over the Grapevine, so named some people believe because of its interwoven freeways: cars take one road and trucks another, but they cross over northbound traffic creating a twisted vine of freeways. There are a variety of fast food restaurants and a Starbucks just before you head over the Grapevine and there's virtually nothing available during the drive itself, so fill up before the drive.
