All these BC South Central hills are a delight! There is above-treeline skiing there, but the mountains in the interior are made of mostly dirt rather than the craggy rock at Whistler or Banff. Most dirt finds its natural angle of repose at about 60%, so you don't get the super-steeps you will find elsewhere. The weather is much drier than the coast, so about half the snowfall, but the snow is light & fluffy (too much so for me, I like snow with substance).
Sun Peaks and Big White are the larger resorts and have the most terrain and nicest hotels and services, so that is where I would spend more of my time. You can cover most terrain at Apex or Silver Star in a day. All these resorts have a good percentage of high-speed lifts. Lifts lines of more than 5 minutes are a rareity.
There is no fog in the mountains... fog gathers in valley bottoms and the sea and hugs the surface. What you ski in is cloud, which is also responsible for precipitation. Search for resorts that get minimal snow, and the resort will have better visibility more often. Of course, there is a down-side to this...
Have a great trip!