Things I would do on a return trip...
-Just spend time in Oregon, probably the central and north part of the state. 
-Check out the Lava Tubes or Volcano National Monument south of Bend
-Plan for at least 2 days at Crater Lake (especially if hiking Cleetwood Cove, that should be a full day activity)
-Drive the west part of Hwy 138 to Roseburg, OR
-Plan for more time at Cannon Beach to accommodate large number of people.  
-Expect there to be fog at coast, and viewing to be limited at times.  You might not get that perfect shot. 
-More time in Bend, OR.  So much to do there!