We stayed in the NIkko after two days at the Sheraton Sapporo. The room we booked was an executive double and was on the 32nd floor.
The good part of the Nikko is definately the location as it is is walkable to all of downtown Sapporo and attached to the JR station for convenient travel to neighboring locations.
The bad of the Nikko is as follows: The room is very small, I would say 30% smaller than the Sapporo, to the point where the two suitcases we had filled most of the open space in the room. My real complaint though lies in the service. Sky Resort Spa is quite nice and is located on the 22nd floor, however, there is a per entrance fee of about 1500 Yen per time even when you have a massage appointment. The Sheraton has a one time fee for your entire stay so you can come and go as you please.
If you have a short trip to Sapporo and minimal luggage, than the Nikko is fine, if you are here for a longer time or have golf clubs or skiis I would recommend you stay elsewhere.

I came back from Sapporo today, and it was excellent stay.
Adjacent to Japan Railway Sapporo station, 40 minutes ride from Chitose international airport, the hotel is convenitently located.
The building is the highest one in Hokkaido -36 floors, so, you can enjoy spacious views of Sappporo from your room.
Staffs are polite and helpful.
The twin-bedded room is spacious enough and modern, like Hyatt brand hotles. Bathroom is also spacious.
A room service is limited (from 19:30 to 23:30), but tasty and very good value for money.
A breakfast buffet was above average. Notice!, after 8 am, there were so many guests who were waiting for seats.
Disliked: There were so many Japanese "Obachan", terribly I hate them.
Overall, I recommend this hotel

I have been in Sapporo 3 times and JR Tower Hotel Nikko Sapporo is the best for me due to the following reasons:

- Location: With its name you might know that this hotel is just adhered to the JR station. And therefore it's very convenient and great for you to be there especially after a long travelling time. The JR Sapporo is a main station so it's also time saving for you to get to other cities.

- Environment: It's in the heart of Sapporo so you can go shopping, eating and walking around the main spots easily.

- Condition: It's a very new and nice hotel. The room, bed and bathroom is big enough with nice view of the city.

- Staff there is nice though some of them may not be very good in English.

It's a bit expensive to stay there but as I booked via travel agent the price cut a lot. It's a bit sad cos I was sick during my stay there.

I would recommend this hotel to you. And I'd definite stay there again if I back to Sapporo.

Excellent Location just on the JR Sapporo Station with a Huge shopping and food plaza! you can taste the Famous Japanese noodles there! JR tower is the tallest building in Sapporo city with marverous night sceneary! Hotel rooms and service are above average!