Newland is the best considering road condition, bike lanes/wide shoulder. It ends at Garden Grove, but coming via Jamboree is OK!
I avoid Beach; I've gone out as far as Buena Park and found Beach excellent much of the way with wide bike lanes, but they periodically get narrow or vanish. In BP, Beach becomes 4 lanes with no bike lanes and the traffic is rude and dangerous! On the way back and future trips, I usually use Goldenwest/Knot. Magnolia is also one I avoid because of long sections without bike paths. Brookhurst is good and bad... use it when no alternative is available.
PCH to Long Beach is great! I recommend riding the beach path, 8.5 miles each way, and continue north to Long Beach... welcome to Surf City (a.k.a. HB); enjoy the ride/visit.