I would say I prefer option A - but perhaps not for the reason you might think.

I like that option because you're spending multiple days in the same campsite. Being that you're going to be in an RV, it's not as big of a deal because you'll be leaving your campsite every day anyway, unlike a tent or trailer where you'd be able to leave everything set up, however, just checking into a campground takes time. If you show up at a busy time, it could easily take 30 minutes to an hour to get checked in and get a feel for how to best park on the site. I wouldn't say that is a dealbreaker, but I'd find that tiresome to have to do that every day and it's something I would factor into your equation.

You mention in option A you're planning to go from Tetons to Calgary via the east? Which route did you have in mind - are you talking about going back up through Yellowstone, maybe even beartooth highway? As Dave mentioned, that is going to take quite a bit of time. Heading from Jackson west towards Idaho Falls, and then up I-15 would certainly make things a lot faster and reduce some of your travel time.

As far as other interim stops, I think Missoula is a nice town that's about halfway between Yellowstone and West Glacier. The last time I was there, I camped at a private campground near Travelers Rest State Park (the state park doesn't have camping).

Helena - Montana's state capitol - could be a place to stop between Tetons and Calgary. I know there's quite a few National Forest campgrounds in that area, although there's probably some private options too.