end is tricky if kids are too small.
I took 7 and 8 years olds and they were okay. Too much smaller and I'd hesitate.
I'll second silver falls. That place is outrageous too. And good for all ages/experience levels.
The coast is great. A good all-around fun spot is pacific city. Sand dunes, plus good beaches, plus plenty to eat around there. And it's not nearly as crowded as Cannon beach.
My favorite beach in Oregon though is neskowin. Look up proposal rock. Great beach with a huge rock thing off the shore. At low tide you can access the rock, climb to the top, and walk almost all the way around it. Lots of cool creatures.
Oh, and my other favorite beach for sure is seal rock. Really great spot with tide pools and a good swimming area.