When we head back to Portland we like to stay at Mountain Gate ... just outside of Redding and before you hit the mountains which I don't like driving at night.
As far as RV parks in Portland .. haven't used any but I drive by Pheasant Ridge near Wilsonville all the time (just south of Portland) - looks nice and is 15 minute drive to downtown. Worth a Google.
Bend has one large expensive/nice RV park .. don't recall the name .. another easy Google. There is also a State Park south of Bend - it's nice but site are a bit tight/close (most of Oregon State Parks have large sites).
If your going to Oregon you need to spend some time on the Coast ... it's unique and nothing like the beaches you have in S Calif .. also has some of the best State Parks in the country.
If your taking long trip .. consider going up I-5 and returning on 101 (at least through Oregon)