I'm originally from Alberta so have visited Banff and Jasper many times. What others say about the Fairmonts (Lake Louise, Jasper Park Lodge and Banff Springs) and Rimrock are similar to my own experience. They are not full luxury hotels, IMO, with mediocre service and lacklustre rooms. That said, along with the Post Hotel in Lake Louise (a relais et chateaux property), they're pretty much your only options for higher end hotel experiences and there are certain room categories that can be quite nice.
In Banff,
my personal preference is the RimRock. The views from the Rimrock are truly spectacular and superior to the Banff Springs because it is built higher up. Also, the
Signature Grandview rooms (Room
#s 700, 701, 702 and 800 - around $700-$1000/night in high season) and Grandview Suites are genuinely good quality for a luxury property. We usually stay at one of the RimRock's Signature Grandviews and they range from 500-700 sq ft, each come with a gas fireplace, exceptionally comfortable king-size bed, sitting area, separate large soaking tub/shower, high quality furnishings and most importantly, world-class views of the township valley and surrounding mountains. These offer the best views in Banff and IMO are the highest quality room in the area as well. Some of the signature grand views come with bathtubs with windows and panoramic views and others with large terraces with bucket-list quality views.
For Jasper, while I have my problems with the Fairmont Jasper Park Lodge (too many lacklustre service experiences in the past), I still think it can be a nice place to visit in the summer. The Lakefront Suite with wood-burning fireplace are tranquil, decently sized and good quality.
The prime tourist spots in the Alberta rockies are all within National Parks. While this is great for conservation, it also means development is restricted such that there's always a mismatch with greater demand than supply. This enables the hotels to get away with less than stellar service and the result is that there is no true luxury hotel in the area. I believe the Fairmonts and Rimrock are all rated 4 diamonds by AAA ,not 5. Still, it's well worth a visit. The mountains are stunning, there are some decent restaurants and the aforementioned hotels do have select room categories that are quite nice.
EDIT: One thing I forgot to add about the Rimrock is that its amenities/facilities are worse than the Banff Springs. I'm not sure it would matter during coronavirus though as I expect the Banff Springs' spa will be closed. Rimrock has a very uninspired spa and an indoor pool that could be out of any 4-star hotel. The Banff Springs' large spa, on the other hand, is fairly impressive.
EDIT 2: One other thing to add is that the RimRock's Signature Grandviews do not come with any dedicated lounge access or special concierge service like Fairmont Gold does at the Banff Springs. Something worth noting if that is important to you.