We visited Sun Peaks as an overnight stay on our road trip through the Rockies back in April. It was really between seasons then, the end of the winter sports/skiing season and before the summer season, so it felt a little "unloved" I think is the best way to put it.
You have to drive quite a way off the main road to get to Sun Peaks resort itself and it clearly has been built in recent years to cater for the winter sports scene.
Nothing wrong with the Sun Peaks Grand hotel, did everything it should. Watch out if you're driving there, as parking cost C$13 for one night! There was still remnants of snow about which did make the place look grubby but I'm sure that would have been cleaned up ready for the next season.
Our room, number 390 was very generous, with double aspect views, very clean and well appointed. The beds were super comfy too. Good tea/coffee making facilities in the room too.
If I was going back to that part of the world I would probably stay there again but possibly not in April for the reasons I mentioned above. Also, every year about the end of April they hold the national children's band practice camp there, so it was full of kids aged about 10-15 years old - very noisy!