The intersection of Richards Boulevard and Interstate 5 is a great place to catch a ride north out of Sac.
Heading north towards Redding on I-5, I took a city bus (42B) to Woodland. Then I kept walking north to find a good on ramp for I-5. A friendly cop picked me up and took me to Dunnigan. There is a really good on ramp with a gas station (December 2017).
South West towards San Francisco, North East towards Reno
You can try your luck on Northgate Boulevard in front of the Quality Inn and the IHOP. Matt&camy had to wait about two hours to get a ride to Rocklin, but cars can definitely pull over.
There is a very good spot at the end of West Capitol Avenue for both directions on I80. Leave Sacramento, crossing the river on the Tower Bridge, heading West. Then find West Capitol Avenue which you can walk down all the way, or you can take a bus. Waiting time direction Reno was 1h15. April 2016.