I just went on a roadtrip with my boyfriend, we drove from Vancouver to Kamloops, stayed with a friend. Then Kamloops to Jasper, to Banff, back to Kamloops then home.
If you pass by Salmon Arm, go to the Barley Station Brewpub right on the highway, I was there for their $16 Prime rib special and OMG it was better than the Keg.
Banff hotels were $200-$300/night in July, if the weather is good most campgrounds would be taken up as well, but it doesn't seem like you guys are the camping types.
I suggest checking out some Japanese cuisine since most of them are pretty authentic. For dining check out this site, it should help:
http://www.taximike.com/
Hot springs is a must, other than that Banff is just another resort town, you walk around the strip, take pictures.
I personally liked Jasper a lot better in terms of scenic, it was breathtaking, and we hiked up the Icefields. Once you've seen Jasper National Park, everythign else seems dull. Great if you're into photography.
Here's another site that might help you out:
http://www.banff-on-a-budget.com/banff-restaurants.html