The onsen was fantastic, so were the restaurants. We ran into several language issues so best to go with a local or if you can speak the language - there are a small handful of staff who could speak English but otherwise, it was usually a comical scene of chickens talking to ducks :)
There are free shuttle pick ups from Sakunami station - the trains run hourly from Sendai station so you can be sure of a yellow bus waiting for you when you get off. I believe there is also ONE daily pick up and drop off at Sendai station - the pick up from Sendai station is at 3pm (i think!) and the bus leaves the onsen at 11am daily, to arrive at Sendai station at 12 noon thereabouts. So if you can't make the 3pm pick up, just take the 40 min train ride to Sakunami station for the hourly pick up.
There is also a free shuttle to and fro Nikka Distillery - a must go if you are staying for more than a night. You need to check with the hotel staff for timings. I'm not sure what other services they had, but worth asking if you can speak japanese...
There's little to do in the surrounding areas (within walking distance). We only found a really quaint convenience store (unlike your usual Lawsons/FamilyMarts, so manage your expectations!), a great bbq place and a little ramen store. So do drive or be prepared to just lounge around in the onsen - not necessarily a bad thing :)
Finally, the buffet dinner is also fantastic - make time for that!