Klamath Falls KOA is a good stop over place on your way to Crater Lake. This KOA has all the amenities that you expect from a KOA. I especially like the pool on a hot day. It has a few unique cabins that seem like a fun place to stay along with a few tent camping spots. 

There's a shopping center within a 10 min walk from the campground that has a grocery and sporting goods store along a pizza, BBQ and Thai restaurant. 

Cell Service: Good