For the coast, it is a matter of stopping at state parks and waysides or just turnouts to explore. There are some great rocky tidepools along the way near Yachats, Waldport and Seal Rock. The Oregon Coast Aquarium is very good, at the southern tip of the bridge before you enter Newport. The hike out to end of Cape Lookout is nice. A stop at the Tillamook Cheese Factory just north of Tillamook gets you some tasty cheese curds or fresh ice cream. Near the northern tip you can drive on the beach for about 10 miles from Gearhart to the old shipwreck of the Peter Iredale. The entire Oregon coast is public access from sealine to vegetation so there is plenty more to see and do than time to do it.
The gorge is a very nice drive. If you go that way, get on the Old Columbia River Highway around where I-84 turns to 65mph.
The drive north up the Idaho panhandle into Canada is very pretty.
If you need anything in the area I am in Salem and Kevin/WagonGear is in Eugene.
Have fun!