When visiting Nikko, I stayed at the Hotel Sunshine Kinugawa in Kinugawa Onsen.
It was a lovely place to stay. Large tamami rooms with spacious bathroom attached. Our room could have easily accommodated 4-6 people. The building and interior are a bit old, but clean and functional. And the staff were really warm and friendly; very helpful.
They have a fun mini arcade that includes a train conductor game! Much harder than it looks.
The onsen was lovely - they had a lukewarm pool (~40 degrees celsius) and a warmer indoor pool. The outside rotenburo has a nice view of the mountains and is very peaceful.
The dinner was a buffet meal with chefs making fresh Tempura and sauteeing beef on the spot. Honestly, I would describe the food as adequate to good, but there was a good deal of variety and we all enjoyed it.
The online prices seem pretty reasonable, with the cheapest plan starting at 8000 yen per person.