I suspect it would work out cheaper to hire an SUV long term thant to hire multiple short termers and pay lots of connectinf 4 pax flights
The views from Bannf to Kamloops are quite spectaular (I thibk the term is God's own country) and then you can stop in a the shops in Kamloops on the way through a stock the back of the SUV up with groceries on the way up to SP.
I'd definitely do the drive over two days to reduce the risk of driving tired, allow for weather, and give you some time to stop and smell the roses. Revelstoke is a nice little town too.
I'm sure your kids would benefit from seeing the countryside as well
(I hate sitting in airport depatrure lounges

)