Sterling Nainital is a beautiful resort with spacious rooms and courteous staff. It is a bit far from naini lake (around 7km) however still worth staying. The leading road from lake to resort is good to drive. Food is good. Manoj Bisht and other staff working at restaurant are very good.
(Check out beautiful photos and interesting information about Sterling Nainital by Sterling here. https://www.sterlingholidays.com/resorts-hotels/nainital)