Well,
Grog, I can tell you right now, you won't miss out on hills. The western coastline of north america, particularly in Oregon is nothing like the worn thin eastern coastline. It's ALL hills. Good towns, Tillamuck, Cannon Beach, Seaside.
lots of other good towns that you will pass on the way. Lots of incredible vistas, and great biking.
Just don't get your hopes up about swimming in the ocean too much; it's usually too cold to really enjoy immersing yourself in (although in August you might)