We (family) did this a few years back.
Van was from Alldrive. We picked it up and dropped it off in Vancouver, but they do one-way hire too (with an added cost). I’d easily go to them again.
3 of us, so we went for the smallest “5th wheel” type. That’s basically a big pickup with an articulated trailer on the back. The advantage is that you can drop off the trailer at a site, then use the pickup for gadding about. With the campervan types, you have to pack everything away every time you want to travel somewhere. Fine if you’re constantly on the move, but we’d spend 2/3 days in each place, getting to know it a bit better, then move on.
You also end up with a massive pickup truck – think 6 Litre Turbodiesel with huuuuuge torque 🙂
Get aircon in the trailer. We didn’t and cooked all the way from Banff back to Vancouver.
Fuel is cheap(er) but consumption is higher. I worked it out around 15 mpg. Overall cost per mile was about the same as the UK (at that time – it might have changed).
Fantastic holiday. We all want to go back, but need to save up a bit of cash.
Anything else? Let me know here or PM me