To calibrate how burly the trails are up here, I got my brakes bled on July 6 and dropped the bike off today for another bleed.
Whistler and Nelson are largely similar. All the trails were just brutally hard, and I imagine it's largely a consequence of the climate. It's borderline rainforest there, so the ground is really soft and rooty. You couldn't put in a buff trail if you tried - it would rapidly get eroded down to the roots. So, people get big bikes. That's a positive feedback loop as those bikes damage trails more than cross-country bikes. It's a downhillers wet dream, but I ended up frustrated and sore.
Fernie was great. It's a tiny town with about as many trails as Park City. The trails are challenging cross country rides - good amounts of uphill singletrack, tough and fun downhills. I'd especially reccomend Eric's Trail and Oh Dear to any UT-expert level riders. Both are classic singletrack, Eric's only has a few especially steep spots, but I spent most of Oh Dear behind the saddle. There's also a ski resort (that I didn't ride) and a ton of trails near the resort. I only rode a couple of those - Dem Bones is a great ride down and would probably be a fun climb. It's just buff singletrack winding down a wide ridgeline.
I camped with some Golden locals in Whistler. One of them (a Maxxis rider) told me that I had to ride Kicking Horse, their new ski resort. Kicking Horse has a 4000 foot vertical, a steep top, a grizzly refuge underneath the gondola, and is brand spanking new. Maybe 20% of the descent is still on the lift road, but there's definitely a good day of downhilling there. Hard trails, challenging stunts that are either bypassable or good to learn on, and good trails. The only problem is that there's nothing that's not tiring on a 6-inch, 30 pound bike. The easiest trail there was built like Bobsled, but the downhill bikes have chopped it up so much that it's an exhausting ride with tons of braking. Others are harder. I did ride a couple 10-inch wide stunts, which is as small as I've ridden. A favorite was bigger - a roller coaster to a wooden berm.
I just spent a night in Canmore, but liked the guys at Couloir Bike and Ski there. Get off at the Silvertip exit, it's on your right 100 yards W of the A+W.