Highway #20 WA is one of the 10 best motorcycle roads in the USA -- enough said [I have personally ridden it several times].
Although they have been working hard on improving the highway [the width and the straightness] over the past several years the highway between Hope and Princeton was and is notorious. I would recommend the following namely:
The highway #1 in Canada East from Abbotsford BC [4 miles N of Sumas WA] to Hope BC is 4 lane divided. At Hope your options are to continue North on #1 to Kamloops [ which is: known as the "Trans Canada" - it is mostly 2 lanes with wide shoulders and numerous passing lanes - and has lots of transport truck traffic depending on the time of day as the climbs are less severe than the "Cocahalla"] OR continue East from Hope on highway #5 all the way to Kamloops [which is: known as the "The Cocahalla" - it is 4 lane divided all the way but has 2 long climbs]
At Kamloops you re-join the Trans Canada and continue East to Lake Louise then Banff [a great drive through the heart of the Rocky Mountains].
For your return I would suggest doubling back, from Banff, on the Trans Canada to "Castle Junction" - highway #1 & highway # 93] and then head South on # 93 through Whitefish MT to Missoula MT where you can then take US I-90 West ....
Depending on your degree of mobility [ a towed ] you could take a day trip North from Lake Louise on # 93 "the Banff / Jasper highway" to the Saskatchewan River crossing or further North to the Columbia Ice Fields or all the way to Jasper [the only other resort town located in the park]. Going all the way to Jasper would mean an overnighter but depending upon the weather it is without doubt the most scenic drive in the Canadian Rockies. You would be doubling back on your return
Drive safe and have a great adventure