This is probably one of the nicest RV resorts/parks that we have visited that is also freeway (I5) close. Toutle River RV Park is near Kelso, WA which is only about an hour from Portland.
Great amenities, mostly large pull-throughs, fire pits, pool, kids activities (including storytelling & movies), etc.
Road noise is light which is surprising given its proximity to the freeway. There is, of course, the mandatory train tracks that are nearby. The nights we stayed there it wasn’t bad and did not interfere with our sleep.
They even have some pet wash stations and a spot (pull-over) for RV washing where they provide a hose and brush.