This quiet mountain village boasts a number of nice onsens. Though there's less traditional ambiance here, the famous gorge (pictured below) makes for a nice diversion between soaks.
Getting to Akiu requires a car, or a long train then bus ride, so it's not a great spot for higaeri day-trippers. Check the schedules prior to setting out and make sure you get an early start. Once in Akiu, the centrally located tourist info center can offer onsen suggestions, most of which are the hotel/spa kind. The rice fields, pretty gorge, and mountains are wonderful scenery, but definitely come for the peace and quiet, not the night life. A stay in one of the larger hotels might mean some conversations at the bars, but -- day or night -- there's little else to do here other than soak.