On your way to/from the Oregon Coast from Portland, and if the weather is cooperating, you might want to take a detour (about 20 minutes) to Jewell Meadows Wildlife Area in Jewell. Jewell Meadows is home to about 200 Roosevelt Elk, as well as other wildlife, and has three turn-outs where you (hopefully) can see the elk grazing, resting, cavorting, and doing basically whatever elk do.
The best time to see the elk is in the cooler weather and either early in the morning or dusk - at other times during the day they tend to hang-out at the tree line. When we were there this time, we saw many mother elk and their adolescents, as well as quite a few male elk. The middle turn-out has restrooms, an interpretive display, as well as picnic tables.
Be sure to bring your binoculars, a camera with a good zoom lens (we only had our "baby" camera), and listen closely.....we heard some males bugling this time! Oh yeah, it's FREE! :-)